U.S. patent application number 12/659720 was filed with the patent office on 2010-09-23 for electronic circuit board manufacturing method.
This patent application is currently assigned to FUJIFILM Corporation. Invention is credited to Seiichi Inoue, Hiroshi Kawakami, Wataru Ono, Junichi Yoshida.
Application Number | 20100239749 12/659720 |
Document ID | / |
Family ID | 42737898 |
Filed Date | 2010-09-23 |
United States Patent
Application |
20100239749 |
Kind Code |
A1 |
Yoshida; Junichi ; et
al. |
September 23, 2010 |
Electronic circuit board manufacturing method
Abstract
An electronic circuit board is formed by a pattern forming step
for forming a conductive pattern of an electronic circuit board by
applying a metal colloid solution on a base material by an inkjet
method and a coagulant application step for applying a coagulant
solution at least on the conductive pattern by a deposition
method.
Inventors: |
Yoshida; Junichi;
(Kanagawa-ken, JP) ; Inoue; Seiichi;
(Kanagawa-ken, JP) ; Ono; Wataru; (Fujinomiya-shi,
JP) ; Kawakami; Hiroshi; (Fujinomiya-shi,
JP) |
Correspondence
Address: |
AKERMAN SENTERFITT
8100 BOONE BOULEVARD, SUITE 700
VIENNA
VA
22182-2683
US
|
Assignee: |
FUJIFILM Corporation
Tokyo
JP
|
Family ID: |
42737898 |
Appl. No.: |
12/659720 |
Filed: |
March 18, 2010 |
Current U.S.
Class: |
427/97.3 ;
427/98.4 |
Current CPC
Class: |
H05K 3/1208 20130101;
H05K 2203/122 20130101; H05K 3/1283 20130101; H05K 2201/0116
20130101; H05K 3/125 20130101; H05K 2203/125 20130101 |
Class at
Publication: |
427/97.3 ;
427/98.4 |
International
Class: |
B05D 5/12 20060101
B05D005/12 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 19, 2009 |
JP |
2009-068513 |
Jul 23, 2009 |
JP |
2009-172024 |
Claims
1. An electronic circuit board manufacturing method, comprising: a
pattern forming step for forming a conductive pattern of an
electronic circuit board by applying a metal colloid solution on a
base material by an inkjet method; and a coagulant application step
for applying a coagulant solution at least on the conductive
pattern by a deposition method.
2. The electronic circuit board manufacturing method of claim 1,
wherein an application amount of the coagulant solution is greater
than an application amount of the metal colloid solution.
3. The electronic circuit board manufacturing method of claim 1,
wherein an application area of the coagulant solution is not
greater than an application area of the metal colloid solution.
4. The electronic circuit board manufacturing method of claim 1,
wherein a solvent of the coagulant solution has compatibility with
a solvent of the metal colloid solution.
5. The electronic circuit board manufacturing method of claim 1,
wherein the base material is a reception layer-equipped base
material having a porous reception layer formed on a surface
thereof.
6. An electronic circuit board manufacturing method, comprising,
when forming a conductive pattern of an electronic circuit board by
applying a metal colloid solution on a base material by an inkjet
method: a coagulant solution application step for applying a
coagulant solution on the base material; and a pattern forming step
for forming the conductive pattern on the coagulant solution with
the metal colloid solution.
7. The electronic circuit board manufacturing method of claim 6,
wherein a solvent of the coagulant solution has compatibility with
a solvent of the metal colloid solution.
8. The electronic circuit board manufacturing method of claim 6,
wherein the base material is a reception layer-equipped base
material having a porous reception layer formed on a surface
thereof.
9. An electronic circuit board manufacturing method, comprising,
when forming a conductive pattern of an electronic circuit board on
a reception layer-equipped base material, which is a base material
with a porous reception layer having a coagulant provided on a
surface of the base material, a pattern forming step for forming
the conductive pattern by applying a metal colloid solution on the
reception layer-equipped base material by an inkjet method.
10. The electronic circuit board manufacturing method of claim 9,
wherein the reception layer-equipped base material is provided by a
solution application step in which a mixed solution of a porous
reception layer forming component and a coagulant is applied on the
base material.
11. The electronic circuit board manufacturing method of claim 9,
wherein the reception layer-equipped base material is provided by a
reception layer forming coagulant solution application step in
which a porous reception layer forming component solution and a
coagulant solution are applied on the base material.
12. The electronic circuit board manufacturing method of claim 11,
wherein the reception layer forming coagulant solution application
step is a step comprising a reception layer forming solution
application step for applying a reception layer forming solution
having the porous reception layer forming component and a coagulant
application step for applying the coagulant solution, which is
incorporated in the reception layer forming solution application
step.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to an electronic circuit board
manufacturing method, and more particularly to an electronic
circuit board manufacturing method for forming a wiring of an
electronic circuit board.
[0003] 2. Description of the Related Art
[0004] Heretofore, as methods for forming a pattern of a wiring
portion (conductor portion) of an electronic circuit board (printed
wiring board), subtractive method, semi-additive method, and
additive method are known.
[0005] The subtractive method is a method for forming a pattern of
conductor portion (wiring pattern) by removing an unnecessary
portion of a metal layer formed on a base material while leaving a
necessary portion. In contrast, the semi-additive or additive
method is a method for additively forming a pattern of conductor
portion on a base material. In each case, the pattern of conductor
portion is formed based on a photolithography technology.
[0006] The subtractive method, semi-additive method, and additive
method will now be described a bit further using FIGS. 7 to 9. Note
that each of FIGS. 7 to 9 schematically illustrates a cross-section
of a printed wiring board.
[0007] FIG. 7 illustrates a process of forming a pattern of
conductor portion when the subtractive method is used. In the
subtractive method, a conductive layer 202 of copper foil is formed
on each side of an insulating base material (insulation layer) 200
to provide a copper clad lamination as shown in Step 1. Then, as
shown in Step 2, through-hole (via hole) 206 is made in the copper
clad lamination 204 and, as shown in Step 3, conductive metal layer
208 is formed on the surface of each conductive layer 202 and on
the inner wall of the through-hole 206 by electroplating or
electroless plating, whereby the formation of through-hole 206 is
completed.
[0008] After though-hole 206 is formed, a resist layer 210 is
formed on the surface of conductive metal layer 208 on conductive
layer 202 with a dry film resist (DFR), a liquid resist, or the
like. Then, patterning is performed on resist layer 210 by exposing
the layer to radiant rays from a photo tool (not shown) and
developing.
[0009] After resist layer 210 is patterned, a portion of conductive
layer 202 and a portion of conductive metal layer 208 not covered
by resist layer 210 are removed by etching, as shown in Step 5 and,
as shown in Step 6, resist layer 210 is removed and a printed
wiring board is formed.
[0010] FIG. 8 illustrates a process of forming a pattern of
conductor portion when the semi-additive method is used. In the
semi-additive method, in insulating base material 200 shown in Step
1, though-hole 206 is formed, as shown in Step 2 and a conductive
metal layer 208 is formed on each surface of insulating base
material 200 and on the inner wall of through-hole 206 by
electroless plating, as shown in Step 3.
[0011] After conductive metal layer 208 is formed, resist layer 210
is formed with a dry film resist (DFR) or a liquid resist. Then,
patterning is performed on resist layer 210 by exposing the layer
to radiant rays from a photo tool (not shown) and developing.
[0012] After resist layer 210 is patterned, a conductive metal 212
is formed by electroplating with a portion of conductive metal
layer 208 not covered by resist layer 210 as the seed layer, as
shown in Step 5. Then, as shown in Step 6, resist layer 210 is
removed and, as shown in Step 7, conductive metal layer 208 not
covered by conductive metal 212 is removed, whereby a printed
wiring board is formed.
[0013] FIG. 9 illustrates a process of forming a pattern of
conductor portion when the additive method is used. In the additive
method, in insulating base material (insulation layer) 200 shown in
Step 1, though-hole 206 is formed, as shown in Step 2. Then, resist
layer 210 is formed with a dry film resist (DFR), a liquid resist,
or the like and further resist layer 210 is patterned by exposing
the resist to radian rays from a photo tool (not shown) and
developing, as shown in Step 3.
[0014] After resist layer 210 is formed, conductive metal layer 208
is formed on a portion of insulating base material 200 not covered
by resist layer 210 and on the inner wall of through-hole 206 by
electroless plating, as shown in Step 4. Finally, resist layer 210
is removed and a printed wiring board is formed, as shown in Step
5.
[0015] The method for forming a desired wiring pattern by forming a
resist pattern based on the photolithography technology described
above requires time for providing a photomask. Further, the method
also requires resist exposure and development processing for
forming a resist pattern aside from the etching for removing an
unnecessary portion of wiring metal. Consequently, formation of a
wiring pattern takes time and cost. The method also poses a problem
of treating a large amount of waste liquid due to the exposure and
development processing. Still further, cracking or detachment may
occur in the pattern or otherwise the base material itself is
damaged if the type and amount of solvent used, and immersion time
are not selected appropriately.
[0016] Consequently, a method for forming a pattern of wiring
portion of an electronic circuit board based on conductive fine
particle dispersed ink drawing has recently been proposed. In the
conductive fine particle dispersed ink drawing, a wiring pattern is
formed by pattering a liquid-like body (metal colloid solution)
which includes a conductive fine particle material (metal colloidal
particles) directly on a base material according to a desired
wiring pattern using inkjet printing method.
[0017] The conductive fine particle dispersed ink drawing method
does not require a mask so that it requires a less number of
manufacturing steps in comparison with the method that forms a
resist pattern by photolithography technology and then forms a
desired wiring pattern. Further, the conductive fine particle
dispersed ink drawing method does not require the exposure and
development step so that the waste liquid treatment is no longer
required.
[0018] As one of such conductive fine particle dispersed ink
drawing methods, a method in which a reception layer is formed on a
base material and a metal colloid solution is applied to the
reception layer and heat-treated to contact the conductive fine
particles included in the metal colloid solution to each other,
thereby inducing conductivity is proposed as described, for
example, in U.S. Pat. No. 7,356,921.
[0019] Another method is also proposed in which, when forming a
mesh pattern for electromagnetic shielding by applying a liquid
which includes a functional material to a transparent base material
by inkjet method, a first ink (e.g., cationic or multivalent metal
salt) is discharged on the base material and then a second ink
(e.g., anionic) is discharged so as to overlap with the first ink
to contact the second ink with the first ink on the base material,
thereby forming a conductive mesh pattern as described, for
example, in Japanese Unexamined Patent Publication No.
2008-066568.
[0020] In the methods described in U.S. Pat. No. 7,356,921 and
Japanese Unexamined Patent Publication No. 2008-066568, however,
prolonged baking at a high temperature is required in order to
induce conductivity in the fine particle materials. Consequently,
base materials on which a wiring pattern can be formed are limited
to heat resistive materials. In addition, high running and
manufacturing costs are required with an inevitable large equipment
size for high temperature processing. If a low heat resistive base
material is used, then the conductivity of the wiring pattern
formed may be reduced due to a low heating temperature. In the
method describe in Japanese Unexamined Patent Publication No.
2008-066568, if the first and second inks are not appropriately
brought into contact, the two types of inks are not mixed together
and a desired electrical property may not be obtained. Further, it
is necessary to drop inks such that the first and second inks
contact appropriately. Consequently, ink drop control becomes
complicated, which makes it difficult to form a complicated
conductive pattern.
[0021] The present invention has been developed in view of the
circumstances described above, and it is an object of the present
invention to manufacture an electronic circuit board easily with a
low cost.
SUMMARY OF THE INVENTION
[0022] A first electronic circuit board manufacturing method of the
present invention is a method, including:
[0023] a pattern forming step for forming a conductive pattern of
an electronic circuit board by applying a metal colloid solution on
a base material by an inkjet method; and
[0024] a coagulant application step for applying a coagulant
solution at least on the conductive pattern by a deposition
method.
[0025] As for the "deposition method", any method may be used as
long as it is capable of discharging and applying a coagulant
solution on a base material and, for example, an inkjet method, a
dispenser method, or the like may be used.
[0026] The term "applying a coagulant solution at least on the
conductive pattern" as used herein refers to not only the case in
which the solution is applied on the entire surface of the
conductive pattern but also the case in which the solution is
applied on the conductive pattern and an intervening space of the
pattern and the case in which the solution is applied on a portion
of the conductive pattern.
[0027] In the first electronic circuit board manufacturing method
of the present invention, an application amount of the coagulant
solution may be greater than an application amount of the metal
colloid solution.
[0028] Further, in the first electronic circuit board manufacturing
method of the present invention, an application area of the
coagulant solution may be not greater than an application area of
the metal colloid solution.
[0029] A second electronic circuit board manufacturing method of
the present invention is a method, including, when forming a
conductive pattern of an electronic circuit board by applying a
metal colloid solution on a base material by an inkjet method:
[0030] a coagulant solution application step for applying a
coagulant solution on the base material; and [0031] a pattern
forming step for forming the conductive pattern on the coagulant
solution with the metal colloid solution.
[0032] In the first and second electronic circuit board
manufacturing methods of the present invention, a solvent of the
coagulant solution may have compatibility with a solvent of the
metal colloid solution.
[0033] Further, in the first and second electronic circuit board
manufacturing methods of the present invention, the difference in
SP (Solubility Parameter) value between the solvent of the metal
colloid solution and the solvent of the coagulant solution is in
the range from 1 to 15.
[0034] Still further, in the first and second electronic circuit
board manufacturing methods of the present invention, the base
material may be a reception layer-equipped base material having a
porous reception layer formed on a surface thereof.
[0035] A third electronic circuit board manufacturing method of the
present invention is a method, including, when forming a conductive
pattern of an electronic circuit board on a reception
layer-equipped base material, which is a base material with a
porous reception layer having a coagulant provided on a surface of
the base material,
[0036] a pattern forming step for forming the conductive pattern by
applying a metal colloid solution on the reception layer-equipped
base material by an inkjet method.
[0037] The term "a porous reception layer with a coagulant received
on a surface of the base material" as used herein refers to not
only the case in which the porous reception layer with a coagulant
is completely dried but also the case in which the porous reception
layer is half dried or not dried.
[0038] In the third electronic circuit board manufacturing method
of the present invention, the reception layer-equipped base
material may be provided by a solution application step in which a
mixed solution of a porous reception layer forming component and a
coagulant is applied on the base material.
[0039] In this case, the mixed solution may be obtained by adding
the coagulant to a reception layer forming solution having the
porous reception layer forming component, by adding the porous
reception layer forming component to a coagulant solution, or by
in-line mixing the reception layer forming solution and the
coagulant solution.
[0040] Further, in the third electronic circuit board manufacturing
method of the present invention, the reception layer-equipped base
material may be provided by a reception layer forming coagulant
solution application step in which a porous reception layer forming
component solution and a coagulant solution are applied on the base
material.
[0041] In this case, the reception layer forming coagulant solution
application step may be a step including a reception layer forming
solution application step for applying a reception layer forming
solution having the porous reception layer forming component and a
coagulant application step for applying the coagulant solution,
which is incorporated in the reception layer forming solution
application step.
[0042] Further, in this case, the reception layer forming solution
and coagulant solution may be applied one after another at the same
time, or the reception layer forming solution is applied first and
then the coagulant solution during or after the drying process of
the reception layer forming solution.
[0043] According to the first electronic circuit board
manufacturing method of the present invention, a coagulant solution
is applied by a deposition method at least on a conductive pattern
formed with a metal colloid solution.
[0044] According to the second electronic circuit board
manufacturing method of the present invention, a coagulant solution
is applied on a base material and then a conductive pattern is
formed on the coagulant solution with a metal colloid solution.
[0045] According to the third electronic circuit board
manufacturing method of the present invention, a conductive pattern
is formed on a reception layer-equipped base material, which is a
base material with a porous reception layer having a coagulant
provided on a surface of the base material, with a metal colloid
solution.
[0046] Consequently, the cohesiveness of the metal colloidal
particles in the metal colloid solution is enhanced by simply
leaving the solution at room temperature without heating due to the
presence of the coagulant solution. Since the cohesiveness of the
metal colloidal particles is enhanced, the standing time at room
temperature may be reduced, resulting in a reduced manufacturing
time. Further, since the cohesiveness of the metal colloidal
particles is enhanced, a conductive pattern may be formed without
spoiling the conductivity. Still further, any heating equipment is
required since heating process is not required, whereby the
manufacturing cost may be reduced. Further, the base material needs
not to have high heat resistivity, which increases the selection
freedom of base material and a general purpose base material may be
used. Thus, according to the present invention, electronic circuit
boards may be manufactured efficiently at a low cost without
increasing the size of the manufacturing facilities.
[0047] In particular, in the second electronic circuit board
manufacturing method of the present invention, an entire base
material surface application method, such as a bar coating method
may be selected as the application method of the coagulant
solution. Consequently, the coating process of coagulant solution
may be simplified, resulting in a reduced manufacturing cost.
Further, the coagulation action is started immediately after the
metal colloid solution is applied on the base material, so that the
interference between adjacently applied metal colloid solutions
during the application of the metal colloid solution may be
prevented.
[0048] Further, in the first electronic circuit board manufacturing
method of the present invention, the cohesiveness of the metal
colloidal particles may be further enhanced by applying the
coagulant solution in an amount greater than an application amount
of the metal colloid solution and whereby the standing time at room
temperature may further be reduced.
[0049] Still further, in the first electronic circuit board
manufacturing method of the present invention, the consumed amount
of coagulant solution may be reduced by limiting the application
area of the coagulant solution smaller than the application area of
the metal colloid solution. Further, this will result in that the
coagulant solution is applied concentratingly only on a required
portion, so that the coagulation of the metal colloidal particles
may be efficiently enhanced, which may further reduce the standing
time at room temperature. Still further, the conductive pattern
formed with the metal colloid solution may be prevented from
wet-spreading, since the coagulant solution is applied only on a
required portion.
[0050] Further, in the third electronic circuit board manufacturing
method of the present invention, a reception layer-equipped base
material is used. Still further, in the first and second electronic
circuit board manufacturing methods of the present invention, the
base material may be turned into a reception layer-equipped base
material having a porous reception layer formed on a surface
thereof. This will result in that the metal colloid solution is
applied on the reception layer, so that the adhesion between the
base material and conductive pattern formed with the metal colloid
solution may be increased. Consequently, even when the solvent of
the metal colloid solution and the coagulant solution are applied
on top of each other, the shape of the conductive pattern formed
with the metal colloid solution is ensured. This allows, therefore,
the application amount of the coagulant solution to be increased,
whereby the cohesiveness of the metal colloidal fine particles may
further be enhanced. Further, the conductive pattern formed is free
from defects as wiring, such as a short circuit or an open
circuit.
BRIEF DESCRIPTION OF THE DRAWINGS
[0051] FIG. 1 is a drawing conceptually illustrating an electronic
circuit board manufacturing method according to a first embodiment
of the present invention.
[0052] FIGS. 2A to 2D are drawings for explaining an application
area of a coagulant.
[0053] FIG. 3 is a drawing conceptually illustrating an electronic
circuit board manufacturing method according to a second embodiment
of the present invention.
[0054] FIG. 4 is a drawing conceptually illustrating an electronic
circuit board manufacturing method according to a third embodiment
of the present invention.
[0055] FIG. 5 is a drawing conceptually illustrating an electronic
circuit board manufacturing method according to a fourth embodiment
of the present invention.
[0056] FIG. 6 is a table of SP values of various types of
solvents.
[0057] FIG. 7 is a drawing schematically illustrating a wiring
pattern forming method when subtractive method is used.
[0058] FIG. 8 is a drawing schematically illustrating a wiring
pattern forming method when semi-additive method is used.
[0059] FIG. 9 is a drawing schematically illustrating a wiring
pattern forming method when additive method is used.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0060] Hereinafter, embodiments of the present invention will be
described with reference to the accompanying drawings. FIG. 1 is a
drawing conceptually illustrating an electronic circuit board
manufacturing method according to a first embodiment of the present
invention.
[0061] First, as shown in Step 1, reception layer 12 is formed on
one surface of base material 10. Note that reception layer 12 may
be formed on each surface of base material 10. Further, base
material 10 having reception layer 12 formed thereon in advance may
be used.
[0062] Next, as shown in Step 2, metal colloid solution 14 is
discharged by an inkjet method and applied on the surface of
reception layer 12 in a conductive pattern. More specifically,
metal colloid solution 14 is discharged by the inkjet method based
on image data of the conductive pattern, whereby metal colloid
solution 14 is applied on the surface of reception layer 12. The
detail of metal colloid solution 14 will be described later.
[0063] As the inkjet method, any of the thermal method, piezo
method, and electrostatic method may be used, but the piezo method
is more preferably used. In the case of the thermal method, it is
preferable that metal colloid solution 14 is a solution which
includes an aqueous vehicle, and in the case of the electrostatic
method, it is necessary to charge metal colloidal particles of
metal colloid solution 14 by coating the particles with a
resin.
[0064] Right after metal colloid solution 14 is discharged on the
surface of reception layer 12 by the inkjet method in the manner as
described above, the droplets of metal colloid solution 14 are
arranged side by side, as shown in Step 2, but immediately
thereafter the droplets penetrate into reception layer 12 to form
conductive metal portion 16 which is trapezoidal in cross-section
as shown in Step 3. Where reception layer 12 has a high porosity,
metal colloidal particles included in metal colloid solution 14 may
enter into the porosities and conductive metal portion 16 shaped in
an upside-down trapezoid of Step 3, having a lower side shorter
than an upper side, may sometimes be formed.
[0065] Here, when metal colloid solution 14 is applied by an inkjet
method, a coagulant solution for metal colloid solution 14 is also
applied by the inkjet method in a latter stage, so that two process
steps may be performed within the same equipment. Therefore, the
equipment may be downsized and the numbers of equipment units and
process steps may be reduced in comparison with the case in which
an electronic circuit board is manufactured by photolithography.
Further, as the numbers of equipment units and process steps are
reduced, so does the overall processing time, which is favorable
from the viewpoint of productivity.
[0066] When metal colloid solution 14 penetrates into reception
layer 12, a dispersant dispersed in metal colloid solution 14 is
absorbed with the solvent at the same time by reception layer 12,
whereby dispersion collapse of metal colloid solution 14 is
started. In order to fully induce conductivity of metal colloidal
particles in metal colloid solution 14, i.e., in order to cause the
metal colloidal particles to have a sufficiently low resistance as
a conductive pattern, however, a heat treatment or a standing
period of several days at room temperature is required. In the
first embodiment, therefore, coagulant solution 20 is applied to
the conductive pattern portion formed of metal colloid solution 14
in place of such processing as described above. More specifically,
as shown in Step 4, a coagulant solution 20 is applied on the
conductive pattern (conductive metal portion 16) of applied metal
colloid solution 14 by the inkjet method. The detail of the
coagulant solution 20 will be described later.
[0067] Preferably, the coating amount of coagulant solution 20 is
as much as possible so that the entirety of conductive metal
portion 16 formed of metal colloid solution 14 is soaked with
coagulant solution 20, as shown in Step 5, within a range in which
the pattern of conductive metal portion 16 does not collapse. For
this purpose, coagulant solution 20 is dropped and applied to the
conductive pattern area at least once and preferably a plurality of
times. It is preferable that an inkjet head capable of discharging
a larger droplet than that of an inkjet head for discharging metal
colloid solution 14 is used for the discharge of coagulant solution
20. Further, coagulant solution 20 may be applied by a dispenser
method instead of the inkjet method. This may increase the coating
amount of coagulant solution.
[0068] Preferably, the coating amount of coagulant solution 20 is
as much as possible, but the optimum amount of coagulant solution
20 is that which, when coagulant solution 20 is applied over the
entire area of conductive pattern formed of metal colloid solution
14, is kept by the surface tension of coagulant solution 20 within
the entire area of the conductive pattern without overflowing.
Here, the entire area of conductive pattern as used herein refers
to the area on which a conductive pattern is formed and an area
corresponding to a spacing of the pattern (i.e., area of reception
layer 12). More specifically, for example, when coagulant solution
20 is applied on a conductive pattern in which three conductive
metal portions 16 are formed side by side at a predetermined
spacing as shown in FIG. 2A, a rectangular area, including areas of
reception layer 12 present between each of the three conductive
metal portions 16, is the entire area of the conductive pattern. In
this case, coagulant solution 20 is applied to the rectangular
area, including the areas of reception layer 12 present between
each of conductive metal portions 16, as shown in FIG. 2B. Note
that, in FIGS. 2A to 2D, coagulant solution 20 is indicated in
gray.
[0069] Further, coagulant solution 20 may be applied only to
conductive metal portions 16, as shown in FIG. 2C. Alternatively,
coagulant solution 20 may be applied only to inner areas of
conductive metal portions 16, as shown in FIG. 2D. This may avoid
the application of coagulant solution 20 to unnecessary areas and
the amount of coagulant solution 20 used may be reduced.
[0070] In the first embodiment, coagulant solution 20 may be
applied only to the conductive pattern area (including entire area
of conductive pattern described above) by the use of inkjet method
as shown in FIGS. 2B to 2D, whereby application of coagulant
solution 20 to unnecessary areas is not required. Consequently,
cracking, detachment, or swelling of the conductive pattern may not
be induced and also reception layer 12 may not be damaged.
[0071] After coagulant solution 20 is applied in the manner as
described above, a drying treatment is performed as required. This
completes the formation of a conductive pattern of conductive metal
portion 16, as shown in Step 6. As the drying method, drying at
room temperature is sufficient. After coagulant solution 20 is
applied, allowing the pattern to stand for at least several hours
at room temperature may induce conductivity so that the standing
time may be reduced in comparison with the case in which coagulant
solution 20 is not applied.
[0072] By the method described above, an electronic circuit board
is manufactured.
[0073] Next, a second embodiment of the present invention will be
described. FIG. 3 is a drawing conceptually illustrating an
electronic circuit board manufacturing method according to the
second embodiment of the present invention.
[0074] In the second embodiment, first coagulant solution 20 is
applied over the entire surface of base material 10, as shown in
Step 1. In the second embodiment, although the inkjet method or
dispenser method may be used, an overall coating method, such as a
bar coating method, is more preferably used. This may simplify the
coating process of coagulant solution 20, whereby the manufacturing
cost of an electronic circuit board may be reduced.
[0075] Then, as shown in Step 2, metal colloid solution 14 is
discharged by an inkjet method and applied on the surface of base
material 10 having coagulant solution 20 applied thereon in a
conductive pattern. More specifically, metal colloid solution 14 is
discharged by the inkjet method based on image data of the
conductive pattern, whereby metal colloid solution 14 is applied on
the surface of base material 10 having coagulant solution 20
applied thereon.
[0076] Right after metal colloid solution 14 is discharged by the
inkjet method in the manner as described above, the droplets of
metal colloid solution 14 are arranged side by side, as shown in
Step 2, but immediately thereafter the droplets turn into
conductive metal portion 16 which is trapezoidal in cross-section
as shown in Step 3.
[0077] Thereafter, a drying treatment is performed as required.
This completes the formation of a conductive pattern of conductive
metal portion 16, as shown in Step 4. As the drying method, drying
at room temperature is sufficient. After coagulant solution 20 is
applied, allowing the pattern to stand for at least several hours
at room temperature may induce conductivity so that the standing
time may be reduced in comparison with the case in which coagulant
solution 20 is not applied.
[0078] In the second embodiment, coagulant solution 20 may be
applied over the entire surface of base material 10 after forming
reception layer 12 on base material 10, as in the first embodiment.
Further, the coagulant solution 20 may be applied only to an area
of base material 10 in which a conductive pattern is formed.
[0079] Next, a third embodiment of the present invention will be
described. FIG. 4 is a drawing conceptually illustrating an
electronic circuit board manufacturing method according to the
third embodiment of the present invention. First, as shown in Step
1, coagulant added reception layer 30, to which a coagulant is
added, is formed on one surface of base material 10. Coagulant
added reception layer 30 may be formed, for example, by applying a
mixed solution of a porous reception layer forming component and a
coagulant over the entire surface of base material 10. Here, the
mixed solution may be prepared by adding the coagulant to a
reception layer forming solution which includes the porous
reception layer forming component, adding the porous reception
layer forming component to a coagulant solution, or in-line mixing
the reception layer forming solution and coagulant solution. The
application of the mixed solution may be carried out by the inkjet
method, dispenser method, or overall coating method, such as bar
coating method, as in the second embodiment.
[0080] In the third embodiment, coagulant added reception layer 30
may be formed on each surface of base material 10. Further, base
material 10 having coagulant added reception layer 30 formed
thereon in advance may be used. Coagulant added reception layer 30
may be formed only in the area of base material 10 in which a
conductive pattern is formed. Methods for forming base material 10
and coagulant added reception layer 30, and coagulant added
reception layer 30 will be described later.
[0081] Next, as shown in Step 2, metal colloid solution 14 is
discharged by an inkjet method and applied on the surface of
reception layer 30. More specifically, metal colloid solution 14 is
discharged by the inkjet method based on image data of the
conductive pattern, whereby metal colloid solution 14 is applied on
the surface of base material 10 having coagulant added reception
layer 30 formed thereon.
[0082] Right after metal colloid solution 14 is discharged by the
inkjet method in the manner as described above, the droplets of
metal colloid solution 14 are arranged side by side, as shown in
Step 2, but immediately thereafter the droplets turn into
conductive metal portion 16 which is trapezoidal in cross-section
as shown in Step 3. At this time, the coagulant added to coagulant
added reception layer 30 spreads into conductive metal portion 16.
Thereafter, a drying treatment is performed as required. This
completes the formation of a conductive pattern of conductive metal
portion 16.
[0083] Next, a fourth embodiment of the present invention will be
described. FIG. 5 is a drawing conceptually illustrating an
electronic circuit board manufacturing method according to the
fourth embodiment of the present invention. The electronic circuit
board manufacturing method according to the fourth embodiment is a
method in which formation of coagulant added reception layer 30 in
the third embodiment is described in detail.
[0084] In the fourth embodiment, as shown in Step 1, reception
layer forming solution 40 having a porous reception layer forming
component is applied over the entire surface of base material 10.
Then, as shown in Step 2, coagulant solution 20 is applied over
reception layer forming solution 40 during a drying step of
reception layer forming solution 40. In this state, reception layer
forming solution 40 is not yet dried, so that the application of
coagulant solution 20 causes reception layer forming solution 40
and coagulant solution 20 to be mixed together and turned into
coagulant added reception layer 30. In the coagulant added
reception layer 30, however, coagulant solution 20 is distributed
on the upper side of reception layer forming solution 40. The
coagulant solution 20 may be applied simultaneously with reception
layer forming solution 40. Also, in this case, reception layer
forming solution 40 and coagulant solution 20 are mixed together,
but coagulant solution 20 is distributed on the upper side of
reception layer forming solution 40. The application of reception
layer forming solution 40 and coagulant solution 20 may be carried
out by the inkjet method, dispenser method, or overall coating
method, such as bar coating method, as in the second
embodiment.
[0085] Then, as shown in Step 3, metal colloid solution 14 is
discharged by an inkjet method and applied on the surface of base
material 10 in a conductive pattern during a drying step of
reception layer forming solution 40 and coagulant solution 20
(coagulant added reception layer 30). Right after metal colloid
solution 14 is discharged by the inkjet method in the manner as
described above, the droplets of metal colloid solution 14 are
arranged side by side on the upper side of reception layer forming
solution 40 of coagulant added reception layer 30, as shown in Step
3, but immediately thereafter the droplets turns into conductive
metal portion 16 which is trapezoidal in cross-section as shown in
Step 4. Thereafter, when reception layer forming solution 40 and
coagulant solution 20 are dried, the formation of coagulant added
reception layer 30 and a conductive pattern of conductive metal
portion 16 is completed, as shown in Step 5.
[0086] Here, in the fourth embodiment, application of metal colloid
solution 14 is performed during a drying step of reception layer
forming solution 40 and coagulant solution 20 (coagulant added
reception layer 30), but the metal colloid solution 14 may be
applied after reception layer forming solution 40 and coagulant
solution 20 are dried. In this case, the application mode of metal
colloid solution 14 is identical to that of the third
embodiment.
[0087] In the first to fourth embodiments, plating may be
performed, as required, on conductive metal portion 16 to provide a
plated coating for preventing oxidization, mounting an electronic
component, and the like.
[0088] Further, in the first to fourth embodiments, solder resist
processing may be performed, as required, on conductive metal
portion 16 for protecting the conductive pattern, preventing
oxidization, preventing short circuiting due to contact with other
metals, and the like.
[0089] Although reception layer 12 is formed on base material 10 in
the first embodiment, but metal colloid solution 14 may be applied
directly to base material 10 without forming reception layer
12.
[0090] Further, in the first to fourth embodiments, electronic
circuit boards are manufactured, but the method of the present
invention is not limited to this and may also manufacture
electromagnetic wave shielding film for PDP that requires
transparency and an electromagnetic wave shielding function
(conductivity effect).
[0091] Preferably, an electromagnetic wave shielding film
(conductivity metal portion) for PDP manufactured by the present
invention has a surface resistance value of not greater than
10.OMEGA./.quadrature., more preferably not greater than
2.5.OMEGA./.quadrature. when used as a material of transparent
electromagnetic wave shield and not greater than
1.5.OMEGA./.quadrature. when used in a consumer plasma television
using a PDP, and further preferably not greater than
0.5.OMEGA./.quadrature..
[0092] Preferably, the conductive metal portion, when used in an
electromagnetic shielding film for PDP, has a line width not
greater than 20 .mu.m and a line interval not smaller than 50
.mu.m. Further, the conductive metal portion may have a section
having a greater line width than 20 .mu.m for ground connection.
Preferably, conductive metal portion has a line width not greater
than 15 .mu.m, more preferably not greater than 10 .mu.m, and
further preferably not greater than 7 .mu.m from the viewpoint of
making less recognizable.
[0093] Preferably, the conductive metal portion, when used in an
electromagnetic shielding film for PDP, has an aperture ratio not
smaller than 85%, more preferably not smaller than 90%, and further
preferably not smaller than 95% from the viewpoint of transmittance
of visible light. The "aperture ratio" as used herein refers to a
ratio of area portions without a thin line forming a mesh to the
entire area. For example, the aperture ratio of a square grid mesh
with a line width of 10 .mu.m and a pitch of 200 .mu.m is 90%.
Preferably, the conductive metal portion of the present invention
has an aperture ratio not greater than 98% from the viewpoint of
the relationship between the values of surface resistance and line
width, although there is not a specific upper limit.
[0094] Preferably, the conductive metal portion, when used in an
electromagnetic shielding film for PDP, has a thickness as thin as
possible for the application of display because a thinner thickness
may provide a wider viewing angle. From this viewpoint, it is
preferable that a layer of conductive metal supported by the
conductive metal portion has a thickness less than 9 .mu.m, more
preferably in the range from 0.1 .mu.m to less than 5 .mu.m, and
further preferably in the range from 0.1 .mu.m to less than 3
.mu.m.
[0095] Materials for forming base material 10, reception layer 12,
conductive metal portion 16, and coagulant solution 20 will be
described in detail.
[0096] There is not any specific restriction on base material 10
and the following may be used: papers, such as inkjet papers, resin
laminated papers, resin films, resin substrates, silicon
substrates, ceramics substrates, glass substrates, and the like.
Further, metal base materials, such as aluminum, having an
insulated surface may also be used.
[0097] As for the materials of resin laminated papers, resin films,
and resin substrates, the following may be cited as examples. That
is, polyester series (polyimide, polyethylene terephthalate,
polyethylene naphthalate, and the like, polycarbonate series,
cellulose ester series, polyarylate series, polysulphone series
(including polyether sulfone), polyethylene, polypropylene,
polystyrene, polyvinyl chloride, polyvinylidene chloride, polyvinyl
alcohol, ethylene-vinylalcohol, syndiotactic polystyrene series,
polycarbonate, cycloolefin polymer CARTON, manufactured by JSR
Corporation), ZEONEX.RTM. and ZEONOR.RTM. (Nippon Zeon Co., Ltd),
polymethylpentene, polyether ketone, polyether ether ketone,
polyether ketone imide, polyamide, fluorine resin, nylon,
polymethylmethacrylate, polyacrylate series, polyarylate series,
triacetylcellulose, and the like may be used. The resin film and
resin substrate may be used in the form of a single layer, but they
may be used as a multilayer film having two or more layers stacked
on top of each other.
[0098] As for base material 10 for manufacturing an electromagnetic
wave shielding film, for example, resin films, such as polyimide
film, polyamide-imide film, polyamide film, polyester film,
glass-epoxy substrates, silicon substrates, ceramics substrates,
glass substrates, and the like described in Japanese Unexamined
Patent Publication No. 2008-066568. From the viewpoint of
handlability, however, sheet-like resin films are preferably used.
Electromagnetic wave shielding films require a high transparency,
and it is, therefore, preferable to use a transparent resin film or
a glass substrate as the base material for manufacturing an
electromagnetic wave shielding film. Further, a base material
colored to a degree that does not hinder the required transparency
may also be used.
[0099] In this case, there is not any specific restriction on the
material of the resin film and those described above may be used.
The resins described above may be used in the form of a single
layer, but also as a multilayer film having two or more layers
stacked on top of each other. As base material 10 for manufacturing
an electromagnetic wave shielding film, a polyethylene
terephthalate film, a polyethylene naphthalate film, or a cellulose
ester film is preferably used from the viewpoint of transparency,
heat resistance, handlability, and economy. Among them, the
cellulose ester film is more preferably used from the viewpoint of
transparency, isotropy, adhesiveness, and the like.
[0100] Reception layer 12 used in the present invention is a porous
reception layer which includes at least one of cationic-modified
self-emulsifying polymer, inorganic fine particle, polyvinyl
alcohol having a saponification value of 82 to 98 mol %, water
soluble aluminum compound, zirconium compound, and cross-linking
agent as the layer forming component.
<Cationic-Modified Self-Emulsifying Polymer>
[0101] Reception layer 12 of the present invention includes a
"cationic-modified self-emulsifying polymer". The
"cationic-modified self-emulsifying polymer" as used herein refers
to a polymer that can spontaneously become a stable emulsified
dispersion substance in an aqueous dispersion solution without
using or with a very small amount of emulsifier or surfactant.
Quantitatively speaking, the "cationic-modified self-emulsifying
polymer" represents a high-molecular material stably having
emulsification and dispersibility with a concentration of not less
than 0.5 mass % in an aqueous dispersion solution at room
temperature of 25.degree. C. As for the concentration, not less
than 1 mass % is preferable and not less than 3 mass % is more
preferable.
[0102] More specifically, the "cationic-modified self-emulsifying
polymer" includes, for example, polyaddition system or
polycondensation system polymers having a cationic group, such as
primary to tertiary amino groups, quaternary ammonium group, and
the like.
[0103] Vinyl polymerization system polymers effective as the
polymers include, for example, polymers obtained by polymerizing
the following vinyl monomers. That is, acrylic acid and methacrylic
acid esters (ester groups are alkyl groups which may have a
substituent, or aryl groups, which include, for example, methyl
group, ethyl group, n-propyl group, isopropyl group, n-butyl group,
sec-butyl group, tert-butyl group, hexyl group, 2-ethylhexyl group,
tert-octyl group, 2-chloroethyl group, cyanoethyl group,
2-acetoxyethyl group, tetrahydrofurfuryl group, 5-hydroxypentyl
group, cyclohexyl group, benzyl group, hydroxyethyl group,
3-methoxybutyl group, 2-(2-methoxyethoxy) ethyl group,
2,2,2-tetrafluoroethyl group, 1H,1H,2H,2H-perfluorodecyl group,
phenyl group, 2,4,5-tetramethylphenyl group, 4-chlorophenyl group,
and the like), vinyl esters, more specifically, aliphatic
carboxylic acid vinyl esters which may have a substituent (e.g.,
vinyl acetate, vinyl propionate, vinyl butyrate, vinyl isobutyrate,
vinyl caproate, vinyl chloroacetate, and the like), aromatic
carboxylic acid vinyl esters which may have a substituent (e.g.,
vinyl benzoate, 4-methyl vinyl benzoate, vinyl salicylate, and the
like), acrylamides, more specifically, acrylamide,
N-monosubstituted acrylamide, N-disubstituted acrylamide
(substituents are alkyl groups which may have a substituent, aryl
groups, or silyl groups, which include, for example, methyl group,
n-propyl group, isopropyl group, n-butyl group, tert-butyl group,
tert-octyl group, cyclohexyl group, benzyl group, hydroxymethyl
group, alkoxymethyl group, phenyl group, 2,4,5-tetramethylphenyl
group, 4-chlorophenyl group, trimethylsilyl group, and the like),
methacrylamides, more specifically, methacrylamide,
N-monosubstituted methacrylamide, N-disubstituted methacrylamide
(substituents are alkyl groups which may have a substituent, aryl
groups, or silyl groups, which include, for example, methyl group,
n-propyl group, isopropyl group, n-butyl group, tert-butyl group;
tert-octyl group, cyclohexyl group, benzyl group, hydroxymethyl
group, alkoxymethyl group, phenyl group, 2,4,5-tetramethylphenyl
group, 4-chlorophenyl group, trimethylsilyl, and the like), olefins
(e.g., ethylene, propylene, 1-pentene, vinyl chloride, vinylidene
chloride, isoprene, chloroprene, butadiene, and the like), styrenes
(e.g., styrene, methyl styrene, isopropyl styrene, methoxy styrene,
acetoxy styrene, chloro styrene, and the like), vinyl ethers (e.g.,
methyl vinyl ether, butyl vinyl ether, hexyl vinyl ether, methoxy
ethyl vinyl ether, and the like), and the like.
[0104] As other vinyl monomers, the following are cited: crotonic
acid ester, itaconic acid ester, maleic acid diester, fumaric acid
diester, methyl vinyl ketone, phenyl vinyl ketone, methoxy ethyl
vinyl ketone, N-vinyl oxazolidone, N-vinyl pyrrolidone, methylene
malononitrile, diphenyl-2-acryloyloxyethyl phosphate,
diphenyl-2-methacryloyloxyethyl phosphate,
dibutyl-2-acryloyloxyethyl phosphate,
dioctyl-2-methacryloyloxyethyl phosphate, and the like
[0105] As for monomers having a cationic group, for example, those
having a tertiary amino group, such as dialkylaminoethyl
methacrylate, dialkylaminoethyl acrylate, and the like may be
cited.
[0106] Polyurethanes applicable to the cationic-modified
self-emulsifying polymer include, for example, polyurethanes
synthesized by variously combining the following diol compounds
with diisocyanate compounds and through polyaddition reaction.
[0107] Specific diol compounds include ethylene glycol,
1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol,
2,3-butanediol, 2,2-dimethyl-1,3-propanediol, 1,2-pentanediol,
1,4-pentanediol, 1,5-pentanediol, 2,4-pentanediol,
3,3-dimethyl-1,2-butanediol, 2-ethyl-2-methyl-1,3-propanediol,
1,2-hexanediol, 1,5-hexanediol, 1,6-hexanediol, 2,5-hexanediol,
2-methyl-2,4-pentanediol, 2,2-diethyl-1,3-propanediol,
2,4-dimethyl-2,4-pentanediol, 1,7-heptanediol,
2-methyl-2-propyl-1,3-propanediol, 2,5-dimethyl-2,5-hexanediol,
2-ethyl-1,3-hexanediol, 1,2-octanediol, 1,8-octanediol,
2,2,4-trimethyl-1,3-pentanediol, 1,4-cyclohexanedimethanol,
hydroquinone, diethylene glycol, triethylene glycol, dipropylpyrene
glycol, tripropylpyrene glycol, polyethylene glycol (average
molecular weight=200, 300, 400, 600, 1,000, 1,500, or 4,000),
polypropylene glycol (average molecular weight=200, 400, or 1,000),
polyester polyol, 4,4'-dihydroxy-diphenyl-2,2-propane,
4,4'-dihydroxyphenyl sulfone, and the like.
[0108] Specific diisocyanate compounds include methylene
diisocyanate, ethylene diisocyanate, isophorone diisocyanate,
hexamethylene diisocyanate, 1,4-cyclohexane diisocyanate,
2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 1,3-xylylene
diisocyanate, 1,5-naphthalene diisocyanate, m-phenylene
diisocyanate, p-phenylene diisocyanate,
3,3'-dimethyl-4,4'-diphenylmethane diisocyanate,
3,3'-dimethylbiphenylene diisocyanate, 4,4'-biphenylene
diisocyanate, dicyclohexylmethane diisocyanate, methylenebis
(4-cyclohexyl diisocyanate), and the like.
[0109] As for the cationic groups of polyurethane having a cationic
group, cationic groups, such as primary to tertiary amines,
quaternary ammonium salts, and the like are cited. As for the
cationic-modified self-emulsifying polymer used in the present
invention, urethane resins having such cationic groups as tertiary
amine and quaternary ammonium salt are preferably used.
[0110] Polyurethane having a cationic group may be obtained, for
example, by using a cationic group introduced diol when forming the
polyurethane as described above. In the case of quaternary ammonium
salt, polyurethane having a tertiary amino group may be
quaternarized by a quaternarizing agent.
[0111] Each of the diol compounds and diisocyanate compounds usable
for synthesizing the polyurethane may be used solely or in
combination with one or more of other compounds in various
proportions depending on the purpose (for example, control of the
polymer glass transition temperature (Tg), improving solubility,
providing compatibility with a binder, and improving stability of a
dispersion).
[0112] Polyesters applicable to the cationic-modified
self-emulsifying polymer include, for example, polyesters
synthesized by variously combining the following diol compounds
with dicarboxylic acid compounds and through polycondensation
reaction.
[0113] The dicarboxylic acid compounds include oxalic acid, malonic
acid, succinic acid, glutaric acid, dimethylmalonic acid, adipic
acid, pimelic acid, .alpha.,.alpha.-dimethylsuccinic acid,
acetonedicarboxylic acid, sebacic acid, 1,9-nonanedicarboxylic
acid, fumaric acid, maleic acid, itaconic acid, citraconic acid,
phthalic acid, isophthalic acid, terephthalic acid,
2-butylterephthalic acid, tetrachloroterephthalic acid,
acetylenedicarboxylic acid, poly(ethyleneterephthalate)
dicarboxylic acid, 1,2-cyclohexanedicarboxylic acid,
1,4-cyclohexanedicarboxylic acid, .omega.-poly(ethyleneoxide)
dicarboxylic acid, p-xylylenedicarboxylic acid and the like.
[0114] When polycondensed with a diol compound, each of the
dicarboxylic acid compounds may be used in the form of an alkyl
ester (for example, dimethyl ester) of a dicarboxylic acid or an
acid chloride of a dicarboxylic acid, or in the form of an acid
anhydride such as maleic anhydride, succinic anhydride, and
phthalic anhydride.
[0115] As for the diol compound, those cited in the polyurethane
may be used.
[0116] Polyesters having a cationic group may be obtained by
performing the synthesis using a dicarboxylic acid compound having
a cationic group, such as primary, secondary, or tertiary amine, or
a quaternary ammonium salt.
[0117] Each of the diol compounds, dicarboxylic acids and
hydroxycarboxylate ester compounds used in synthesizing the
polyester may be used solely or in combination with one or more of
other compounds in any proportion depending on the purpose (for
example, control of the polymer glass transition temperature (Tg),
solubility, compatibility with dyes, and stability of
dispersion).
[0118] Preferably, the content of the cationic group in the
cationed self-emulsifying polymer is in the range from 0.1 to 5
mmol/g, and more preferably in the range from 0.2 to 3 mmol/g. When
the content of the cationic group is too low, the polymer
dispersion stability decreases, and when too high, compatibility
with binder decreases.
[0119] As for the cationed self-emulsifying polymer, a polymer
having a cationic group, such as a tertiary amine group or a
quaternary ammonium salt group, is preferably used and an urethane
resin (polyurethane) having a cationic group described above is
more preferably used.
[0120] When the self-emulsifying polymer is used for reception
layer 12, the glass transition temperature thereof is particularly
important. In order to prevent temporal bleeding of a conductive
layer over a long period of time after being formed by the inkjet
method, it is preferable to use a self-emulsifying polymer having a
glass transition temperature less than 50.degree. C. Further, it is
more preferable to use a self-emulsifying polymer having a glass
transition temperature not greater than 30.degree. C., and it is
further preferable to use a self-emulsifying polymer having a glass
transition temperature not greater than 15.degree. C. If the glass
transition temperature is 50.degree. C. or above, the dimensional
stability (curl) may be degraded. There is not any specific
restriction on the lower limit of the glass transition temperature,
and it is around -30.degree. C. for ordinary applications. If the
glass transition temperature is lower than this, the
manufacturability may be reduced when preparing the aqueous
dispersion material.
[0121] Preferably, the mass average molecular weight (Mw) of the
self-emulsifying polymer is in the range from 1,000 to 200,000, and
more preferably in the range from 2,000 to 50,000. A molecular
weight of less than 1,000 may make it difficult to obtain a stable
aqueous dispersion material, while a molecular weight of over
200,000 may reduce the solubility and increase the viscosity of the
liquid, causing it difficult to control the average particle
diameter of the aqueous dispersion material to a small value,
particularly to 0.05 .mu.m or less.
[0122] Preferably, the content of the self-emulsifying polymer in
reception layer 12 is in the range from 0.1 to 30 mass % of the
total solid mass forming reception layer 12, more preferably in the
range from 0.3 to 20 mass %, and further preferably in the range
from 0.5 to 15 mass %. The content of less than 0.1 mass % results
in an insufficient improvement in the temporal bleeding. On the
other hand, the content over 30 mass % reduces the proportion of
inorganic fine particles and a binder component, such as polyvinyl
alcohol, whereby the solvent absorptivity of reception layer 12 for
metal colloid solution 14 is reduced.
[0123] Next, a method for preparing an aqueous dispersion material
of self-emulsifying polymer will be described.
[0124] An aqueous dispersion solution of self-emulsifying polymer
with an average particle diameter of not greater than 0.05 .mu.m
may be obtained by mixing a self-emulsifying polymer with an
aqueous medium, blending an additive as required, and grain
refining the mixed solution using a disperser. Various known
dispersers may be used for obtaining the aqueous dispersion
solution, such as high speed rotary dispersers, medium agitation
type dispersers (such as ball mill, sand mill, and bead mill),
ultrasonic dispersers, colloid mill dispersers, high pressure
dispersers. From the viewpoint of efficient dispersion of granular
mass of fine particles, the medium agitation type disperser,
colloid mill disperser or high pressure disperser is preferably
used.
[0125] Mechanisms of high pressure dispersers (homogenizers) are
detailed in U.S. Pat. No. 4,533,254 and Japanese Unexamined Patent
Publication No. 6 (1994) -047264, and commercially available
dispersers, such as Gaulin Homogenizer (Gaulin Inc.),
Microfluidizer (Microfluidex Inc.), Altimizer (Sugino Machine
K.K.), and the like may be used. A recent high pressure homogenizer
having a mechanism for performing microparticulation in an
ultrahigh pressure jet flow as described, for example, in U.S. Pat.
No. 5,720,551 is particularly effective for emulsifying dispersion
of the present invention. DeBEE2000 (Bee International Ltd.) is as
an example of the emulsifying device using the ultrahigh pressure
jet flow.
[0126] For the aqueous medium used in the dispersing process,
water, na organic solvent, or a mixture thereof may be used.
Organic solvents usable for the dispersion include alcohols, such
as methanol, ethanol, n-propanol, i-propanol, and methoxy propanol,
ketones such as acetone, and methyl ethyl ketone, tetrahydrofuran,
acetonitrile, ethyl acetate, toluene, and the like.
[0127] The self-emulsifying polymer of the present invention may
spontaneously becomes a stable emulsified dispersion material by
itself. In order to speed up or stabilize the emulsifying
dispersion, however, a small amount of dispersant (surfactant) may
be used. For this purpose, various surfactants can be used.
Preferable examples are anionic surfactants, such as fatty acid
salts, alkylsulfate ester salts, alkylbenzenesulfonate salts,
alkylnaphthalenesulfonate salts, dialkylsulfosuccinate salts,
alkylphosphate ester salts, naphthalenesulfonic acid formalin
condensates, polyoxyethylene alkylsulfate ester salts and the like,
and nonionic surfactants, such as polyoxyethylene alkyl ethers,
polyoxyethylene alkylaryl ether, polyoxyethylene fatty acid esters,
sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid
esters, polyoxyethylene alkyl amines, glycerine fatty acid esters,
oxyethylene oxypropylene block copolymers, and the like. Further,
SURFYNOLS (Air Products & Chemicals), an acetylene-based
polyoxyethylene oxide surfactant is also preferably used. Further,
amine oxide type ampholytic surfactants such as
N,N-dimethyl-N-alkylamine oxide, and the like are also preferable.
Further, surfactants listed in Japanese Unexamined Patent
Publication No. 59 (1984)-157636, pp. 37 and 38, and Research
Disclosure No. 308119 (1989) may be used.
[0128] For the stabilization right after the emulsification, a
water-soluble polymer may also be added in addition to the
surfactant described above. As the water-soluble polymer, polyvinyl
alcohols, polyvinyl pyrrolidone, polyethylene oxide, polyacrylic
acid, polyacrylamide, and copolymers thereof are preferably used.
Further, it is also preferable to use natural water-soluble
polymers, such as polysaccharides, casein, gelatin and the
like.
[0129] When dispersing a self-emulsifying polymer in an aqueous
medium by the emulsifying dispersing method, particle size control
is particularly important. In order to increase the purity and
density of metal colloid when a conductive pattern is formed by the
inkjet method, it is necessary to reduce the average particle size
of the self-emulsifying polymer in the aqueous dispersion. More
specifically, it is preferable that the volume average particle
diameter is not greater than 0.05 .mu.m, more preferably not
greater than 0.04 .mu.m, and further preferably not greater than
0.03 .mu.m for reception layer 12 of the present invention.
<Inorganic Fine Particles>
[0130] Reception layer 12 of the present invention includes
inorganic fine particles. Examples of the inorganic fine particles
include silica particles, colloidal silica, titanium dioxide,
barium sulfate, calcium silicate, zeolite, kaolinite, halloysite,
mica, talc, calcium carbonate, magnesium carbonate, calcium
sulfate, boehmite, pseudoboehmite. Among them, silica fine
particles are preferable.
[0131] The silica fine particles have an advantage that they have
an extremely high specific surface area, thereby providing the
layer with a high absorption and retention capacity of the solvent
of metal colloid solution 14. In addition, the silica fine
particles have a low refractive index, so that the dispersion of
the particles to a suitable particle diameter may give reception
layer 12 better transparency. Such transparency of reception layer
12 is important where transparency is required, such as an
electromagnetic wave shielding film for PDP and the like.
[0132] Preferably, the average primary particle diameter of the
inorganic fine particles is not greater than 20 nm, more preferably
not greater than 15 nm, and particularly preferably not greater
than 10 nm. When the average primary particle diameter is not
greater than 20 nm, the absorbing property of reception layer 12
for the solvent of metal colloid solution 14 may be effectively
improved and at the same time the smoothness of the surface of the
layer may be increased.
[0133] The specific surface area of the inorganic fine particles as
determined by the BET method is preferably not smaller than 200
m.sup.2/g, more preferably not smaller than 250 m.sup.2/g, and even
more preferably not smaller than 380 m.sup.2/g. Inorganic fine
particles having a specific surface area not smaller than 200
m.sup.2/g may provide reception layer 12 with high
transparency.
[0134] The BET method in the present invention is one of the
methods for measuring the surface area of powder by gas-phase
adsorption, and more specifically it is a method for measuring the
specific surface area, i.e., the total surface area per g of a
sample, from the absorption isotherm. Nitrogen gas is commonly used
as the adsorption gas, and most widely used is a method of
determining the amount of adsorption by the change in pressure or
volume of the adsorbed gas. One of the most famous equations
describing the adsorption isotherm of multi-molecular system is the
equation of Brunauer, Emmett, and Teller (BET equation). The
surface area is calculated by multiplying the adsorption amount
determined by the BET equation by the surface area occupied by a
single adsorbed molecule.
[0135] Silica fine particles, in particular, have silanol groups on
the surface thereof, and there is easy adhesion between the
particles through the hydrogen bonding of the silanol groups, and
due to an adhesion effect between the particles through the silanol
groups and the water soluble resin, if the average primary size of
the particles is not greater than 20 nm, the porosity ratio of
reception layer 12 is high, and a structure having high
transparency may be formed, whereby the absorbing property of
reception layer 12 for the solvent of metal colloid solution 14 may
be effectively improved.
[0136] Generally, Silica fine particles are largely classified into
wet method particles and dry method (vapor phase process) particles
depending on the manufacturing method. In the wet method, the
silica particles are mainly produced by generating an activated
silica by acid decomposition of a silicate, polymerizing the
activated silica to a proper degree, and coagulating the resulting
polymeric silica to give a hydrated silica. While, in the vapor
phase process, anhydrous silica particles are mainly produced by
high-temperature vapor phase hydrolysis of a silicon halide (flame
hydrolysis process), or by reductively heating and vaporizing
quartz and coke in an electric furnace by applying an arc discharge
and then oxidizing the vaporized silica with air (arc method). The
"vapor-phase process silica" refers to an anhydrous silica particle
produced by a vapor phase process.
[0137] The vapor-phase process silica differs from hydrated silica
in the density of silanol groups on the surface and the presence of
voids therein, and exhibits different properties. The vapor-phase
process silica is suitable for forming a three-dimensional
structure having a higher void ratio. The reason for this is not
clear, but it is presumed that, in the case of hydrated silica,
fine particles have a high silanol group density of 5 to 8 silanol
groups/nm.sup.2 on the surface causing silica particles to
coagulate densely (aggregate), while in the vapor phase process
silica, fine particles have a low silanol group density of 2 to 3
silanol groups/nm.sup.2 on the surface causing silica fine
particles to coagulate sparsely (flocculate), leading to a
structure having a higher void rate.
[0138] In the present invention, the vapor-phase process silica
particles (anhydrous silica) obtained by the dry method is
preferable, and silica particles having a silanol group density of
2 to 3 silanol groups/nm.sup.2 is more preferable.
[0139] The inorganic fine particles favorably used in the present
invention are those of a vapor-phase process silica having a BET
specific surface area not smaller than 200 m.sup.2/g.
<Polyvinyl Alcohol>
[0140] Polyvinyl alcohols used in the present invention have a
saponification value of 92 to 98 mol % (hereinafter, also referred
to as "polyvinyl alcohol according to the present invention"). A
polyvinyl alcohol having a saponification value lower than 82 mol %
causes the viscosity of the coating solution (functional fluid
including the reception layer material) to be increased, thereby
decreasing coating stability. In such a case, it is necessary to
adjust the viscosity by adding methanol, ethanol, acetone, or the
like. On the other hand, a polyvinyl alcohol having a
saponification value greater than 98 mol % causes the absorption
property for the solvent of metal collidal solution 14 to be
decreased. A more preferable value of saponification is in the
range from 93 to 97 mol %.
[0141] Preferably, the polymerization degree of the polyvinyl
alcohol of the present invention is in the range from 1,500 to
3,600, more preferably in the range from 2,000 to 3,500. A
polyvinyl alcohol having a polymerization degree smaller than 1,500
causes cracking in reception layer 12. While a polymerization
degree greater than 4,000 causes the viscosity of coating solution
(functional fluid including the reception layer material) to be
increased which is undesirable.
[0142] In the present invention, a water-soluble resin other than
the polyvinyl alcohol may be used in combination with the polyvinyl
alcohol. Examples of the water-soluble resins for use in
combination with the polyvinyl alcohol include polyvinyl alcohols
(PVAs) having a hydroxyl group as a hydrophilic structural unit and
a saponification value outside of the range described above,
cationic-modified polyvinyl alcohols, anionic-modified polyvinyl
alcohols, silanol-modified polyvinyl alcohols, polyvinylacetal,
cellulosic resins (methylcellulose (MC), ethylcellulose (EC),
hydroxyethylcellulose (HEC), carboxymethylcellulose (CMC),
hydroxypropylcellulose (HPC), etc.), chitins, chitosans, and
starch; hydrophilic ether bond-containing resins such as
polyethylene oxide (PEO), polypropylene oxide (PPO), polyethylene
glycol (PEG), and polyvinylether (PVE); hydrophilic amide group- or
amide bond-containing resins such as polyacrylamide (PAAM) and
polyvinyl pyrrolidone (PVP); and the like. Other examples include
compounds having a carboxyl group as a dissociative group such as
polyacrylate salts, maleic acid resins, alginate salts, gelatins,
and the like.
[0143] Preferably, when the polyvinyl alcohol of the present
invention is used in combination with the water-soluble resin
described above, the ratio of the polyvinyl alcohol of the present
invention to the total amount of the polyvinyl alcohol of the
present invention and the water-soluble resin is in the range from
1 to 30 wt %, more preferably in the range from 3 to 20 wt %, and
further preferably in the range from 6 to 12 wt %.
[0144] Preferably, the content of the polyvinyl alcohol of the
present invention is in the range from 9 to 40 mass %, more
preferably in the range from 12 to 33 mass % with respect to the
total solid mass forming reception layer 12 from the viewpoint of
preventing reduced film strength or cracking when the layer is
dried due to shortage of the resin and preventing reduced
absorption capacity due to blocking of voids by the resin due to an
excessive amount of the resin.
[0145] The polyvinyl alcohol resins contain a hydroxyl group as a
structural unit. Hydrogen bonding between the hydroxyl groups and
the surface silanol groups on silica fine particles allows the
silica fine particles to form a three-dimensional network structure
having secondary particles as the network chain units. This
three-dimensional network structure so constructed seems to be the
cause of easier development of reception layer 12 having a porous
structure having a higher void ratio.
[0146] In base material 10, porous reception layer 12 formed in the
manner as described above rapidly absorbs the solvent of metal
colloid solution 14 by the capillary phenomenon and may form true
circular dots of metal colloid solution 14 without bleeding.
<Content Ratio Between Inorganic Fine Particles and Polyvinyl
Alcohol of the Present Invention>
[0147] When inorganic fine particles (preferably, silica fine
particles; x) is used in combination with the polyvinyl alcohol of
the present invention (if a water-soluble resin is used in
combination with the polyvinyl alcohol, the total mass thereof; y),
the content ratio between them [PB ratio (x/y), mass of inorganic
fine particles relative to 1 part by mass of polyvinyl alcohol of
the present invention] has great impact on the film structure of
reception layer 12. That is, as the PB ratio increases, so do the
void ratio, pore volume, and surface area (per unit mass). More
specifically, it is preferable that the PB ratio (x/y) is 1.5/1 to
10/1 from the viewpoint of preventing reduced film strength and
cracking when the layer is dried due to an extremely large PB ratio
or preventing reduced absorption capacity for the solvent of metal
colloid solution 14 arising from a decreased void ratio by the
filling of voids with the resign due to an extremely small PB
ratio.
[0148] When conveyed through a conveyer system of an ink jet
printer, base material 10 having reception layer 12 formed thereon
may be stressed, it is therefore necessary that reception layer 12
has a sufficient film strength. Further, from the viewpoint of
preventing reception layer 12 from cracking, peeling, or the like
when cut into a sheet, reception layer 12 needs to have a
sufficient film strength. From such viewpoint, it is preferable
that the PB ratio (x/y) is not greater than 5/1, and from the
viewpoint of securing rapid absorption property of reception layer
12 for the solvent of metal colloid solution 14, it is preferable
that the PB radio is not smaller than 2/1.
[0149] For example, when a coating solution (functional fluid
including the reception layer material) prepared by homogeneously
dispersing anhydrous silica fine particles having an average
primary particle diameter of not greater than 20 nm and polyvinyl
alcohol of the present invention in an aqueous solution at a PB
ratio (x/y) in the range from 2/1 to 5/1 is applied on base
material 10 and reception layer 12 is dried, a three-dimensional
network structure having the secondary particles of silica fine
particles as the network chains is formed and a transparent porous
film with an average pore diameter of not greater than 30 nm, a
void ratio in the range from 50 to 80%, specific pore volume of not
smaller than 0.5 ml/g, and a specific surface area of not smaller
than 100 m.sup.2/g is formed easily.
<Cross-Linking Agent>
[0150] Reception layer 12 of the present invention includes a
cross-linking agent. Preferably, reception layer 12 of the present
invention is a porous layer of the polyvinyl alcohol of the present
invention and the water-soluble resin used as required hardened by
the cross-linking reaction of the cross-linking agent.
[0151] The cross-linking agent may be appropriately selected in
relation to the polyvinyl alcohol of the present invention and
water-soluble resin, used as required, included in reception layer
12. In particular, boron compounds are preferable in that they
cause a faster cross-linking reaction. Examples of the boron
compounds include borax, boric acid, borate salts (e.g.,
orthoborate salts, InBO.sub.3, ScBO.sub.3, YBO.sub.3, LaBO.sub.3,
Mg.sub.3(BO.sub.3).sub.2 and CO.sub.3(BO.sub.3).sub.2) diborate
salts (e.g., Mg.sub.2B.sub.2O.sub.5, and CO.sub.2B.sub.2O.sub.5),
metaborate salts (e.g., LiBO.sub.2, Ca(BO.sub.2).sub.2, NaBO.sub.2,
and KBO.sub.2), tetraborate salts (e.g.,
Na.sub.2B.sub.4O.sub.7.10H.sub.2O) pentaborate salts (e.g.,
KB.sub.5O.sub.8.4H.sub.2O, Ca.sub.2B.sub.6O.sub.11.7H.sub.2O, and
CsB.sub.5O.sub.5), and the like. Among them, borax, boric acid and
borates are preferable since they are able to promptly cause a
cross-linking reaction. Particularly, boric acid or borate salt is
preferable, and the combined use of the boric acid or borate salt
and polyvinyl alcohol, a water-soluble resin, is most
preferable.
[0152] Preferably, in the present invention, the cross-linking
agent is included in an amount of 0.05 to 0.50 parts by weight
relative to 1 part by weight of the polyvinyl alcohol of the
present invention, and more preferably in an amount of 0.08 to 0.30
parts by weight. If the content of the cross-linking agent is
within the ranges, the polyvinyl alcohol of the present invention
may be effectively cross-linked, whereby cracking and the like may
be prevented.
[0153] When gelatin is used as a water-soluble resin, the following
compounds other than the boron compounds may be used as the
cross-linking agents.
[0154] Examples of such cross-linking agents include: aldehyde
compounds, such as formaldehyde, glyoxal and glutaraldehyde; ketone
compounds, such as diacetyl and cyclopentanedione; active halogen
compounds, such as
bis(2-chloroethylurea)-2-hydroxy-4,6-dichloro-1,3,5-triazine and
2,4-dichloro-6-S-triazine sodium salt; active vinyl compounds, such
as divinyl sulfonic acid, 1,3-vinylsulfonyl-2-propanol,
N,N'-ethylenebis (vinylsulfonylacetamide) and
1,3,5-triacryloyl-hexahydro-S-triazine; N-methylol compounds such
as dimethylolurea and methylol dimethylhydantoin; melamine resin
such as methylolmelamine and alkylated methylolmelamine; epoxy
resins; isocyanate compounds, such as
1,6-hexamethylenediisocyanate, aziridine compounds such as those
described in U.S. Pat. Nos. 3,017,280 and 2,983,611; carboxyimide
compounds such as those described in U.S. Pat. No. 3,100,704; epoxy
compounds, such as glycerol triglycidyl ether; ethyleneimino
compounds such as 1,6-hexamethylene-N,N'-bisethylene urea;
halogenated carboxyaldehyde compounds, such as mucochloric acid and
mucophenoxychloric acid; dioxane compounds, such as
2,3-dihydroxydioxane; metal-containing compounds, such as titanium
lactate, aluminum sulfate, chromium alum, potassium alum, zirconyl
acetate and chromium acetate; polyamine compounds, such as
tetraethylene pentamine; hydrazide compounds, such as adipic acid
dihydrazide; and low molecular compounds or polymers including at
least two oxazoline groups. These cross-linking agents may be used
solely or in combination with one or more of other compounds.
<Water-Soluble Aluminum Compound>
[0155] Reception layer 12 of the present invention includes a
water-soluble aluminum compound. The use of a water-soluble
aluminum compound may improve the water resistance and temporal
bleeding resistance of a conductive pattern formed. Further, the
use of a aluminum hydroxide compound may reduce the sintering
temperature of the conductive pattern. The mechanism of this is
uncertain, but it is thought that the water-soluble aluminum oxide
interacts with the metal colloid particle dispersant and the
adsorption equilibrium of the dispersant to the metal colloid
particles is lost, whereby the dispersant breaks away from the
particles.
[0156] Examples of the water-soluble aluminum compounds include
inorganic salts, such as aluminum chloride or the hydrates thereof,
aluminum sulfate or the hydrates thereof, ammonium alum, and the
like. Other examples include inorganic aluminum-containing cationic
polymers, such as basic polyaluminum hydroxide compounds. Among
them, basic polyaluminum hydroxide compounds are preferable.
[0157] The basic polyaluminum hydroxide compounds are water soluble
polyaluminum hydroxide compounds stably including multi-nucleated
condensate ions of basic polymers, such as
[Al.sub.6(OH).sub.15].sup.3+, [Al.sub.8(OH).sub.20].sup.4+,
[Al.sub.13(OH).sub.34].sup.5+, [Al.sub.21OH).sub.60].sup.3+, and
the major components thereof are represented by the following
formulae.
[Al.sub.2(OH).sub.nCl.sub.6-n].sub.m5<m<80,1<n<5
Formula 1
[Al(OH).sub.3].sub.nAlCl.sub.31<n<2 Formula 2
Al.sub.n(OH).sub.mCl.sub.(3n-m)0<m<3n,5<m<8 Formula
3
These compounds of various grades are put on the market and may
easily be obtained from Taki Chemical Co. Ltd. in the name of
polyaluminum chloride (PAC), as water treatment agents, Asada
Kagaku Co. Ltd. in the name of polyhydrated aluminium (Paho),
Rikengreen Co. Ltd., in the name of pyurakem WT, Taimei Chemicals
Co. Ltd., in the mane of alphaine 83, and other manufacturers with
the same purpose. These commercially available products may be used
directly in the present invention, but some of the products may
have inappropriately low pH values and in such a case the pH may be
adjusted appropriately before used.
[0158] Preferably, the content of the water-soluble aluminum
compound in reception layer 12 of the present invention is in the
range from 0.1 to 20 mass %, more preferably in the range from 1 to
15 mass %, and most preferably in the range from 2 to 15 mass %
with respect to the total solid mass forming reception layer 12.
The content of water-soluble aluminum compound in the range from 2
to 15 mass % may improve the smoothness, in addition to an
advantageous effect of a reduced sintering temperature.
<Zirconium Compound>
[0159] Reception layer 12 of the present invention includes a
zirconium compound. The use of a zirconium compound may provide an
advantageous effect of an improved water resistance.
[0160] There is not any specific restriction on the zirconium
compounds for use in the present invention, and various compounds
may be use including, for example, zirconyl acetate, zirconium
chloride, zirconium oxychloride, zirconium hydroxychloride,
zirconium nitrate, basic zirconium carbonate, zirconium hydroxide,
zirconium ammonium carbonate, zirconium potassium carbonate,
zirconium sulfate, zirconium fluoride compound, and the like. Among
them, zirconyl acetate is particularly preferable.
[0161] Preferably, the content of the zirconium compound in
reception layer 12 of the present invention is in the range from
0.05 to 5.0 mass %, more preferably in the range from 0.1 to 3 mass
%, and particularly preferably in the range from 0.5 to 2.0 mass %
with respect to the total solid mass forming reception layer 12.
The content of zirconium compound in the range from 0.5 to 2.0 mass
% may improve water resistance without degrading absorption
property.
[0162] In the present invention, a water-soluble polyvalent metal
compound other than the water-soluble aluminum compound and
zirconium compound described above may also be used. Examples of
the other water-soluble polyvalent metal compounds include
water-soluble salts of a metal selected from calcium, barium,
manganese, copper, cobalt, nickel, iron, zinc, chromium, magnesium,
tungsten, and molybdenum.
[0163] Typical examples thereof include calcium acetate, calcium
chloride, calcium formate, calcium sulfate, barium acetate, barium
sulfate, barium phosphate, manganese chloride, manganese acetate,
manganese formate dihydrate, manganese ammonium sulfate
hexahydrate, cupric chloride, ammonium copper (II) chloride
dihydrate, copper sulfate, cobalt chloride, cobalt thiocyanate,
cobalt sulfate, nickel sulfate hexahydrate, nickel chloride
hexahydrate, nickel acetate tetrahydrate, nickel ammonium sulfate
hexahydrate, nickel amidosulfate tetrahydrate, ferrous bromide,
ferrous chloride, ferric chloride, ferrous sulfate, ferric sulfate,
zinc bromide, zinc chloride, zinc nitrate hexahydrate, zinc
sulfate, chromium acetate, chromium sulfate, magnesium sulfate,
magnesium chloride hexahydrate, magnesium citrate nonahydrate,
sodium phosphotungstate, sodium tungsten citrate,
dodecatungstophosphoric acid n-hydrate, dodecatungstosilicic acid
26-hydrate, molybdenum chloride, dodecamolybdophosphoric acid
n-hydrate, and the like.
<Other Components>
[0164] Reception layer 12 of the present invention may include the
following components as required.
[0165] Examples of ultraviolet absorbers include cinnamic acid
derivatives, benzophenone derivatives and benzotriazolyl phenol
derivatives. Specific examples include .alpha.-cyano-phenyl
cinnamic acid butyl ester, o-benzotriazole phenol,
o-benzotriazole-p-chlorophenol, o-benzotriazole-2,4-di-t-butyl
phenol, o-benzotriazole-2,4-di-t-octyl phenol. A hindered phenol
compound amy also be used as an ultraviolet absorber, and phenol
derivatives in which at least one or more of the second place
and/or the sixth place is substituted by a branching alkyl group is
preferable.
[0166] A benzotriazole based ultraviolet absorber, a salicylic acid
based ultraviolet absorber, a cyano acrylate based ultraviolet
absorber, and oxalic acid anilide based ultraviolet absorber or the
like can be also used. Such ultraviolet absorbers are described,
for example, in the following patent documents: Japanese Unexamined
Patent Publication Nos. 47 (1972)-010537, 58 (1983)-111942, 58
(1983)-212844, 59 (1984)-019945, 59 (1984)-046646, 59
(1984)-109055, and 63 (1988)-053544, Japanese Patent Publication
Nos. 36 (1961)-010466, 42 (1967)-026187, 48 (1973)-030492, 48
(1973)-031255, 48 (1973)-041572, 48 (1973)-054965, and 50
(1975)-010726, U.S. Pat. Nos. 2,719,086, 3,707,375, 3,754,919, and
4,220,711.
[0167] An optical whitening agent may also be used as an
ultraviolet absorber, and specific examples include a coumalin
based optical whitening agent. Specific examples are described in
Japanese Patent Nos. 45 (1970)-004699 and 54 (1979)-005324, and the
like
[0168] Examples of antioxidants are described in European Patent
Publication Nos. 223739, 309401, 309402, 310551, 310552, and
459-416, German Patent Publication No. 3435443, Japanese Unexamined
Patent Publication Nos. 54 (1979)-048535, 60 (1985)-107384, 60
(1985)-107383, 60 (1985)-125470, 60 (1985)-125471, 60
(1985)-125472, 60 (1985)-287485, 60 (1985)-287486, 60
(1985)-287487, 60 (1985)-287488, 61 (1986)-160287, 61
(1986)-185483, 61 (1986)-211079, 62 (1987)-146678, 62
(1987)-146680, 62 (1987)-146679, 62 (1987)-282885, 62
(1987)-262047, 63 (1988)-051174, 63 (1988)-089877, 63
(1988)-088380, 66 (1991)-088381, 63 (1988)-113536, 63
(1988)-163351, 63 (1988)-203372, 63 (1988)-224989, 63
(1988)-251282, 63 (1988)-267594, 63 (1988)-182484, 1 (1989)-239282,
2 (1990)-262654, 2 (1990)-071262, 3 (1991)-121449, 4 (1992)-291685,
4 (1992)-291684, 5 (1993)-061166, 5 (1993)-119449, 5 (1993)-188687,
5 (1993)-188686, 5 (1993)-110490, 5 (1993)-1108437, and 5
(1993)-170361, and Japanese Patent Publication Nos. 48
(1973)-043295 and 48 (1973)-033212, and U.S. Pat. Nos. 4,814,262
and 4,980,275.
[0169] Specific examples of the antioxidants include
6-ethoxy-1-phenyl-2,2,4-trimethyl-1,2-dihydroquinoline,
6-ethoxy-1-octyl-2,2,4-trimethyl-1,2-dihydroquinoline,
6-ethoxy-1-phenyl-2,2,4-trimethyl-1,2,3,4-tetrahydroquinoline,
6-ethoxy-1-octyl-2,2,4-trimethyl-1,2,3,4-tetrahydroquinoline,
nickel cyclohexanoate, 2,2-bis(4-hydroxyphenyl) propane,
1,1-bis(4-hydroxyphenyl)-2-ethylhexane,
2-methyl-4-methoxy-diphenylamine, 1-methyl-2-phenyl indole, and the
like.
[0170] These antioxidants can be used solely or in combination with
one or more of other compounds. The antioxidants may be dissolved
in water, dispersed, emulsified, or they may be included in
microcapsules. Preferably, the amount of antioxidant added is in
the range from 0.01 to 10% by mass relative to the total amount of
the coating solution for forming the reception layer.
[0171] Preferably, in the present invention, reception layer 12
includes an organic solvent with a high boiling point so that
curling is prevented. For the high boiling point organic solvent,
water soluble solvents are preferably used. Examples of such water
soluble organic solvents with a high boiling point include the
following alcohols. Namely, ethylene glycol, propylene glycol,
diethylene glycol, triethylene glycol, glycerin, diethylene glycol
monobutylether (DEGMBE), triethylene glycol monobutyl ether,
glycerin monomethyl ether, 1,2,3-butane triol, 1,2,4-butane triol,
1,2,4-pentane triol, 1,2,6-hexane triol, thiodiglycol,
triethanolamine, polyethylene glycol (average molecular weight of
not greater than 400). Among them, diethylene glycol monobutylether
(DEGMBE) is preferable.
[0172] Preferably, the content of the high boiling point organic
solvent in the reception layer coating solution is in the range
from 0.05 to 1% by mass, and particularly preferable in the range
from 0.1 to 0.6% by mass.
[0173] Further, various types of inorganic salts may be included in
order to increase the dispersability of the inorganic fine
particles, and acids or alkalis may be included for pH
adjustment.
[0174] Still further, conductive metal oxide fine particles having
an electron conductivity, for preventing frictional electrification
and peeling electrification, and various types of matting agents,
for reducing the surface friction, may be included to the extent
that does not impair the electrical characteristics as a printed
wiring board.
[0175] A method for forming reception layer 12 using a reception
layer material will now be described in further detail.
[0176] An example method for forming reception layer 12 of the
present invention includes at least the following steps of:
preparing a dispersion solution by dispersing inorganic fine
particles and a zirconium compound by counter-colliding them using
a high pressure disperser or passing them through an orifice;
preparing a reception layer forming solution by adding a
cationic-modified self-emulsifying polymer, a polyvinyl alcohol
having a saponification value of 82 to 98 mol %, and a
cross-linking agent to the dispersion solution; and forming
reception layer 12 by applying a coating solution (functional fluid
including the reception layer material), obtained by in-line mixing
a water soluble aluminum compound with the reception layer forming
solution, on a base material 10.
[0177] Another method for forming reception layer 12 of the present
invention includes at least the following steps of: preparing a
dispersion solution by dispersing inorganic fine particles, a
zirconium compound, and a cross-linking agent by counter-colliding
them using a high pressure disperser or passing them through an
orifice; preparing a reception layer forming solution by adding a
cationic-modified self-emulsifying polymer and a polyvinyl alcohol
having a saponification value of 82 to 98 mol % to the dispersion
solution; and forming reception layer 12 by applying a coating
solution (functional fluid including the reception layer material),
obtained by in-line mixing a water soluble aluminum compound with
the reception layer forming solution, on a base material 10.
[0178] Each of the methods described above is superior in that it
is able to provide a dispersion solution with inorganic fine
particles having a small particle diameter by counter-colliding the
inorganic fine particles and ziruconium compound or the inorganic
fine particles, ziruconium compound, and cross-linking agent using
a high pressure disperser or passing them through an orifice.
[0179] The mixture of inorganic fine particles and ziruconium
compound or the inorganic fine particles, ziruconium compound, and
cross-linking agent is fed into a high pressure disperser in the
state of a dispersion solution including the mixture (preliminary
dispersion solution). Preliminary mixing (preliminary dispersion)
may be performed by an ordinary propeller agitator, turbine
agitator, homomixer agitator, or the like.
[0180] As for the high pressure disperser used for preparing the
dispersion solution, commercially available dispersers generally
called as a high pressure homogenizer are preferably used.
[0181] Typical high pressure homogenizers include Nanomizer (trade
name, manufactured by Nanomizer), Microfluidizer (trade name,
manufactured by Microfluidex Inc.), Ultimizer (manufactured by
Sugino Machine Ltd.), and the like.
[0182] The term "orifice" as used herein refers to a mechanism of
restricting flow path of a straight pipe by inserting a thin plate
with fine holes having a circular or another geometrical shape
(orifice plate) into the pipe.
[0183] Basically, the high pressure homogenizer is an apparatus
that includes a high pressure generation unit for pressurizing
material slurry and the like and a counter-collision or orifice
unit. high pressure pumps generally known as a plunger pump are
preferably used in the high pressure generation unit. Various types
of high-pressure pumps are available, such as single pump type,
twin pump type, triple pump type, and the like, and any type may be
used in the present invention.
[0184] Preferably, the processing pressure when performing the high
pressure counter collision is not less than 50 MPa, more preferably
not less than 100 MPa, and further preferably not less than 130
MPa.
[0185] Preferably, the pressure difference between the inlet and
outlet of the orifice when passing the mixture is not less than 50
MPa, more preferably not less than 100 MPa, and further preferably
not less than 130 MPa, as in the processing pressure described
above.
[0186] Preferably, when counter colliding, the collision speed of
the preliminary dispersion solution, as the relative velocity, is
not less than 50 m/sec, more preferably not less than 100 m/sec,
and further preferably not less than 150 m/sec.
[0187] The linear velocity of a solvent passing through the orifice
may vary according to the pore size of the orifice used, but
preferably not less than 50 m/sec, more preferably not less than
100 m/sec, and further preferably not less than 150 m/sec, as in
the collision speed at the time of counter collision.
[0188] In any of the methods described above, the dispersion
efficiency depends on the processing pressure, and as the
processing pressure increases so does the dispersion efficiency. A
processing pressure exceeding 350 MPa, however, tends to cause a
pressure resistance problem in the piping of the high pressure pump
and a durability problem of the apparatus.
[0189] In any one of the methods described above, there is not any
specific limitation on the number of processing times and normally
it is selected from the range of one to dozens of times. In this
way, the dispersion solution may be obtained.
[0190] When preparing the dispersion solution, a variety of
additives may be added.
[0191] Examples of the additives include various types of nonionic
or cationic surfactants (anionic surfactants are undesirable
because they form aggregation substances), antifoams, nonionic
hydrophilic polymers (polyvinyl alcohol, polyvinyl pyrrolidone,
polyethyleneoxide, polyacrylamide, various sugars, gelatin,
pullulan, and the like), nonionic or cationic latex dispersion
solution, water-miscible organic solvents (ethyl acetate, methanol,
ethanol, isopropanol, n-propanol, acetone, etc.), inorganic salts,
pH adjusters, and the like, which may used as required.
[0192] Water-miscible organic solvents, in particular, are
preferable in that they are able to preventing the formation of
microaggregations when inorganic fine particles (silica) are
preliminarily dispersed. Preferably, the content of water-miscible
organic solvent in the dispersion solution is in the range from 0.1
to 20 mass %, and more preferably in the range from 0.5 to 10 mass
%.
[0193] The pH when preparing an inorganic fine particle (gas-phase
silica) dispersion solution may vary largely according to the type
of the inorganic fine particles (gas-phase silica) used and various
additives used. Generally, however, it is in the range from 1 to 8,
and particularly preferably in the range from 2 to 7. Two or more
additives may be used in the dispersion solution.
[0194] In the method for manufacturing reception layer 12 of the
present invention, a reception layer forming solution is obtained
by adding a cationic modified self-emulsifying polymer, a polyvinyl
alcohol of the present invention, and the like to the dispersion
solution obtained by the method described above. The mixing of the
dispersion solution described above with the cationic modified
self-emulsifying polymer, polyvinyl alcohol of the invention, and
the like may be performed by an ordinary propeller agitator,
turbine agitator, or homomixer agitator.
[0195] In the method for forming reception layer 12 of the present
invention, an in-line mixer preferably used for in-line mixing the
water soluble aluminum compound with the reception layer forming
solution is described, for example, in Japanese Unexamined Patent
Publication No. 2002-85948 but not limited to this.
[0196] The method for forming reception layer 12 of the present
invention may further include a step of cross-linking and hardening
reception layer 12 by applying a basic solution having a pH not
less than 7.1 on reception layer 12 formed on a base material by
applying the coating solution (functional fluid including the
reception layer material) obtained by in-line mixing the water
soluble aluminum compound with the reception layer forming solution
either (1) when the coating solution (functional fluid including
the reception layer material) is applied or (2) during drying step
of reception layer 12 and before reception layer 12 exhibits
decreasing drying.
[0197] Provision of cross-linked and hardened reception layer 12 in
the manner as described above is preferable from the viewpoints of
absorption property of reception layer 12 for the solvent of metal
colloid solution 14 and prevention of cracking.
[0198] In the method for forming reception layer 12 of the present
invention, water, organic solvent, or mixture thereof may be used
as the solvent in each step. Examples of the organic solvents
usable for the coating include alcohols such as methanol, ethanol,
n-propanol, i-propanol, and methoxypropanol, ketones such as
acetone and methylethylketone, tetrahydrofuran, acetonitrile, ethyl
acetate, toluene, and the like.
[0199] The reception layer forming solution may be applied by known
methods, such as extrusion die coater, air doctor coater, blade
coater, rod coater, knife coater, squeeze coater, reverse roll
coater, bar coater, inkjet, and the like.
[0200] A basic solution having a pH not less than 7.1 is applied to
reception layer 12 simultaneously with the application of the
reception layer forming solution or during a drying of reception
layer 12 formed by applying the reception layer forming solution
and before reception layer 12 exhibits a decreasing drying rate.
That is, reception layer 12 is formed favorably by applying the
basic solution having a pH not less than 7.1 on reception layer 12
while the layer shows a constant drying rate after the application
of the reception layer forming solution.
[0201] The basic solution having a pH not less than 7.1 may include
a cross-linking agent as required. The basic solution having a pH
not less than 7.1 may facilitate hardening of the film when used as
an alkali solution. Therefore, it is preferable that the basic
solution has a pH not less than 7.5 and more preferably not less
than 7.9. A pH closer to the acidic side may result in insufficient
cross-linking reaction of the polyvinyl alcohol included in the
reception layer forming solution by the cross-linking agent,
causing problems such as bronzing, inducing defects, such as
cracking, in reception layer 12.
[0202] The basic solution having a pH not less than 7.1 may be
prepared, for example, by adding a metal compound (e.g., 1 to 5%)
and a basic compound (e.g., 1 to 5%), and p-toluenesulfonic acid
(e.g., 0.5 to 3%) as required, to ion-exchange water and agitating
the mixture thoroughly. The above "%" for each component refers to
solid content mass %.
[0203] The term "before reception layer 12 exhibits a decreasing
drying rate" as used herein generally refers to a period of few
minutes just after the application of the coating solution
(functional fluid including the reception layer material). During
the period, coated reception layer shows a phenomenon of "constant
drying rate" in which the content of the solvent (dispersion
medium) decreases linearly with time. The period of the "constant
drying rate" is described, for example, in Chemical Engineering
Handbook (pp. 707 to 712, published by Maruzen Co., Ltd., Oct. 25,
1980).
[0204] The reception layer forming solution is dried after being
applied until reception layer 12 shows a decreasing drying rate as
described above, which is generally implemented at a temperature in
the range from 40 to 180.degree. C. for 0.5 to 10 minutes
(preferably for 0.5 to 5 minutes). The drying period, of course,
varies according to the amount coated, but the range described
above is generally appropriate.
[0205] Next, metal colloid solution 14 for forming conductive metal
portion 16 will be described in detail.
[0206] There is not any specific restriction on metal colloid
solution 14 of the present invention as long as metal colloidal
particles are stabilized as a colloid solution by the presence of a
dispersant.
[0207] Preferably, the metal colloidal particles included in metal
colloid solution 14 are those obtained by reducing a metal compound
under the presence of a polymer dispersant. The metal colloidal
particles can be stably maintained as a metal colloidal particle
solution by the polymer dispersant even in a high concentration
state. Preferably, the metal concentration in the metal colloidal
particle solution is as high as possible, and a preferable value is
not less than 93% by mass and a more preferable value is not less
than 95% by mass.
[0208] The term "metal concentration in the metal colloidal
particle solution" as used herein refers to a mass % of the metal
in the solid content of the metal colloidal particle solution. The
solid content may be obtained by measuring a remaining amount after
heating the solution at 140.degree. C., and the amount of metal may
be obtained by measuring a remaining amount after heating the
solution at 500.degree. C. More specifically, the temperature of
the solution is increased to 140.degree. C. at a rate of 10.degree.
C./min using a TG-DTA, and the solid content is obtained after
maintaining the temperature at 140.degree. C. for 30 minutes.
Thereafter, the temperature is increased to 500.degree. C. at a
rate of 10.degree. C./min and the amount of metal is obtained after
maintaining the temperature at 500.degree. C. for 30 minutes. The
measurement of metal concentration described herein is performed
using the method described above unless otherwise specifically
described.
[0209] The metal compound, the source of the metal colloidal
particles, is a compound that produces metal ions when dissolved in
a solvent and metal colloidal particles are deposited by the
reduction of the ions. There is not any specific restriction on the
metal for forming metal colloidal particles, but a precious metal
or copper is preferably used from the viewpoint of obtaining
conductivity. There is not any specific restriction on the noble
metal and, for example, gold, silver, ruthenium, rhodium,
palladium, osmium, iridium, platinum, and the like may be cited.
Among them, gold, silver, platinum, and palladium are preferable
and silver is particularly preferable in that it has an excellent
conductivity.
[0210] There is not any specific restriction on the metal compound
as long as it includes a noble metal described above or copper.
Examples of such metal compounds include hydrogen
tetrachloroaurate(III) tetrahydrate (chlorauric acid), silver
nitrate, silver acetate, silver perchlorate(IV), hexachloroplatinic
(IV) acid hexahydrate (chloroplatinic acid), potassium
chloroplatinate, copper(II) chloride dihydrate, cupric acetate
monohydrate, copper(II) sulfate, palladium (II) chloride dihydrate,
rhodium (III) trichloride trihydrate, and the like. Each of these
compound may be used solely or in combination with one or more of
other compounds.
[0211] Preferably, the metal compound is used such that the metal
molar concentration in the solvent is not less than 0.01 mol/l. If
the metal molar concentration is less than 0.01 mol/l, the metal
molar concentration of metal colloidal particle solution is too
low, resulting in inefficiency. Preferably, the metal molar
concentration is not less than 0.05 mol/l and more preferably not
less than 0.1 mol/l.
[0212] There is not any specific restriction on the solvent as long
as it is capable of dissolving a metal compound. Typical examples
may be water, organic solvents, and the like. There is not any
specific restriction on the organic solvent, and examples include
alcohols, such as methanol, ethanol, propanol, and butanol;
ketones, such as acetone; esters, such as ethyl acetate;
hydrocarbon system compounds, such as n-heptane, n-octane, decane,
toluene, xylene, cymene, durene, indene, dipentene,
tetrahydronaphthalene, decahydronaphthalene, and cyclohexylbenzene;
ether system compounds, such as ethylene glycol dimethyl ether,
ethylene glycol diethyl ether, ethylene glycol methyl ethyl ether,
diethylene glycol dimethyl ether, diethylene glycol diethyl ether,
diethylene glycol methyl ethyl ether, 1,2-dimethoxyethane,
bis(2-methoxyethyl)ether, and p-dioxane; polar compounds, such as
propylene carbonate, .gamma.-butyrolactone, N-methyl-2-pyrrolidone,
dimethylformamide, dimethyl sulfoxide, and cyclohexanone; apolar
compounds or low polarity compounds, such as terpineol, mineral
spirit, xylene, toluene, tetradecane, dodecane, and 1-decanol which
is a primary alcohol. Each of the compounds may be used solely or
in combination with one or more of other compounds. When the
solvent is a mixture of water and an organic solvent, a water
soluble organic solvent is preferably used. Such organic solvents
include, for example, acetone, methanol, ethanol, and ethylene
glycol. Among them, water, alcohol, and a mixture of water and
alcohol are preferably used as they are suitable for
ultrafiltration performed in a later condensation process. It is
also preferable to use a solvent having a relatively high boiling
point not causing evaporation around room temperature.
[0213] The solvent of metal colloid solution 14 may be determined
in view of the compatibility with the solvent of coagulant solution
20 and difference in SP (solubility parameter) value. Decision of
the solvents of metal colloid solution 14 and coagulant solution 20
will be described later.
[0214] In the mean time, as for the polymer dispersant, it is
preferable to use a amphiphilic copolymer having a structure which
includes a asolvated portion and a functional group highly
compatible with the surface of the metal colloidal particles is
introduced in a high molecular weight polymer.
[0215] Such polymer dispersants are those generally used as a
dispersant when manufacturing a paste, and normally having a number
average molecular weight in the range from 1,000 to 1,000,000. When
the number average molecular weight is less than 1,000,
insufficient dispersion stability may result, while if it exceeds
1,000,000, an excessively high viscosity may result, causing it
difficult to handle. Preferably, the number average molecular
weight is in the range from 2,000 to 500,000 and more preferably in
the range from 4,000 to 500,000.
[0216] There is not any specific restriction on the polymer
dispersant as long as it has the property described above and, for
example, those described in Japanese Unexamined Patent Publication
No. 11 (1999) -080647. Various types of polymer dispersants may be
used and those available in the market may also be used.
Commercially available products include, for example, Solsperse
20000, Solsperse 24000, Solsperse 26000, Solsperse 27000, Solsperse
28000, and Solsperse 41090 (manufactured by Avecia Limited),
Disperbyk 160, Disperbyk 161, Disperbyk 162, Disperbyk 163,
Disperbyk 166, Disperbyk 170, Disperbyk 180, Disperbyk 181,
Disperbyk 182, Disperbyk 183, Disperbyk 184, Disperbyk 190,
Disperbyk 191, Disperbyk 192, Disperbyk-2000, and Disperbyk-2001
(manufactured by Big Chemy), Polymer 100, Polymer 120, Polymer 150,
Polymer 400, Polymer 401, Polymer 402, Polymer 403, Polymer 450,
Polymer 451, Polymer 452, Polymer 453, EFKA-46, EFKA-47, EFKA-48,
EFKA-49, EFKA-1501, EFKA-1502, EFKA-4540, and EFKA-4550
(manufactured by EFKA Chemicals), FLOREN DOPA-158, FLOREN DOPA-22,
FLOREN DOPA-17, FLOREN G-700, FLOREN TG-720W, FLOREN-730W,
FLOREN-740W, and FLOREN-745W (manufactured by Kyoeisha Chemical
Co.), Ajisper PA111, Ajisper PB711, Ajisper PB811, Ajisper PB821,
and Ajisper PW911 (manufactured by AJINOMOTO CO., INC.), Joncryl
678, Joncryl 679, and Joncryl 62 (manufactured by Johnson Polymer
Co., Ltd.), and the like. Each of these agents may be used solely
or in combination with one or more of other agents.
[0217] Preferably, the amount of polymer dispersant used is 10 mass
% with respect to the total amount of the metal in a metal compound
and polymer dispersant. If the amount exceeds 10 mass %, there may
be a case in which the metal concentration in the solid content of
a solution will not be increased to a desired value when
ultrafiltration is performed at a later time. Amore preferable
value for the amount of polymer dispersant used is not greater than
8 mass %, and a further preferable value is not greater than 7 mass
%.
[0218] The metal compound may be reduced using a reducing compound.
As for the reducing compound, amines are preferably used. For
example, if a solution of metal compound and polymer dispersant is
agitated/mixed after adding an amine, metal ions are reduced to
metal. Use of amines eliminates the need to use dangerous or
poisonous reductants and allows metal compounds to be reduced at a
reaction temperature in the range from 5 to 100.degree. C., more
preferably in the range from 20 to 80.degree. C. without requiring
any special heating or light emission device.
[0219] There is not any specific restriction on the amine and, for
example, those described in Japanese Unexamined Patent Publication
No. 11 (1999) -080647 may be used. Further, aliphatic amines, such
as propylamine, butylamine, hexylamine, diethylamine,
dipropylamine, dimethylethylamine, diethylmethylamine,
triethylamine, ethylenediamine, N,N,N',N'-tetramethyl ethylene
diamine, 1,3-diaminopropane,
N,N,N',N'-tetramethyl-1,3-diaminopropane, triethylenetetramine, and
tetraethylene pentamine; alicyclic amines, such as piperidine,
N-methylpiperidine, piperazine, N,N'-dimethylpiperazine,
pyrrolidine, N-methylpyrrolidine, and morpholine; aromatic amines,
such as aniline, N-methylaniline, N,N'-dimethylaniline, toluidine,
anisidine, and phenetidine; aralkylamines, such as benzylamine,
N-methylbenzylamine, N,N-dimethylbenzylamine, phenethylamine,
xylylenediaimine, and N,N,N',N'-tetramethylxylylenediamine. In
addition, alkanolamines, such as methylaminoethanol,
dimethylaminoethanol, triethanolamine, ethanolamine,
diethanolamine, methyldiethanolamine, propanolamine,
2-(3-aminopropylamino) ethanol, butanolamine, hexanolamine,
dimethylamino propanol, and the like may also be cited. Each of the
compounds may be used solely or in combination with one or more of
other compounds. Among them, alkanolamines are preferable and
dimethylaminoethanols are more preferable.
[0220] In addition to the amines, compounds known as reductants,
such as alkali metal borohydride salts including sodium borohydride
and the like, hydrazine compounds, citric acids, acidum
tartaricums, ascorbic acids, formic acids, formaldehydes,
dithionous acids, sulfoxylate derivatives, and the like may also be
used. Among them, citric acid, acidum tartaricums, and ascorbic
acids are preferably used as they are easily obtainable. Each of
the compounds may be used solely or in combination with an amine.
When a citric acid, an acidum tartaricum, or an ascorbic acid is
used in combination with an amine, it is preferable that the citric
acid, acidum tartaricum, or ascorbic acid is in the form of salt.
Further, the reducibility of citric acid or sulfoxylate derivative
may be improved through combined use with iron (II) ions.
[0221] Preferably, the additive amount of the reducing compound is
an amount necessary to reduce the metal in a metal compound or
more. The lesser amount than this may result in insufficient
reduction. There is not a specific upper limit for the amount, but
preferably not greater than 30 times, and more preferably not
greater than 10 times of the amount necessary to reduce the metal
in a metal compound. Further, a method in which the reduction is
induced by emitting light using a high-pressure mercury vapor lamp
may also be used other than the chemical reduction method using the
reducing compounds described above.
[0222] There is not any specific restriction on the method of
adding a reducing compound. For example, a reducing compound may be
added after a polymer dispersant. In this case, for example, the
polymer dispersant is dissolved in a solvent first, then either the
reducing compound or a metal compound is dissolved to obtain a
solution, and finally either the reducing compound or metal
compound remaining is added to the solution, whereby the reduction
process may progress. Alternatively, the polymer dispersant and
reducing compound may be mixed together first, then the mixture may
be added to a solution of the metal compound.
[0223] Through the reduction, a solution that includes metal
colloidal particles with an average particle diameter of 5 to 100
nm may be obtained. The solution includes the metal colloidal
particles and polymer dispersant described above. The term "metal
colloidal particle solution" as used herein refers to a solvent in
which fine metal particles are dispersed and is visually
recognizable as a solution. The metal concentration of metal
colloidal particle solution obtained in the manufacturing process
may be determined by performing measurement with a TG-DTA or the
like as described above. Where such measurement is not performed, a
value calculated from the blending amounts used in the preparation
may be used.
[0224] Next, the reduced solution may be ultrafiltrated. The
reduced metal colloidal particle solution includes miscellaneous
ions, such as chloride ions and the like derived from the materials
and impurities, such as salts produced by the reduction, amine, and
the like, as well as metal colloidal particles and polymer
dispersant. These impurities may adversely influence the stability
of metal colloidal solution 14, and therefore it is desirable to
remove them. For the removal of impurities, electrodialytic
separation method, centrifugal separation method, ultrafiltration
method, or the like may be used. The ultrafiltration method, in
particular, may condense the solution by partly removing the
polymer dispersant, as well as removing impurities, whereby the
metal concentration may be increased.
[0225] Preferably, the solid content formed of metal colloidal
particles and polymer dispersant included in metal colloid solution
14 is in the range from 0.05 to 50% by mass. If the solid content
is less than 0.05%, the metal molar concentration is too low to
perform efficient ultrafiltration, while if it exceeds 50%, removal
of impurities may become difficult.
[0226] Generally, the diameter of a separation target substance for
ultrafiltration is in the range from 1 nm to 5 .mu.m. With the
diameter as the target, the ultrafiltration may remove a portion of
the polymer dispersant together with impurities, whereby the metal
concentration of metal colloidal particles obtained may be
increased. If the diameter is less than 1 nm, an unnecessary
component, such as an impurity and the like, may remain without
passing throught the filtration membrane, while if it exceeds 5
.mu.m, most of metal colloidal particles may pass through the
filtration membrane and high concentration metal colloidal
particles may not be obtained.
[0227] There is not any specific restriction on the filtration
membrane of the ultrafiltration and generally resin membranes, such
as polyacrylonitrile, vinyl chloride/acrylonitrile copolymer,
polysulfone, polyimide, polyamide, and the like, are used. Among
them, polyacrylonitrile and polysulfone are preferable, and
polyacrylonitrile is more preferable. From the viewpoint of
efficient cleaning of filtration membrane generally performed after
ultrafiltration, a filtration membrane that can be reversely
cleaned is preferably used.
[0228] Preferably, the filtration membrane of the ultrafiltration
is a membrane having a molecular weight cut off in the range from
3,000 to 80,000. If the molecular weight cut off is less than
3,000, the unnecessary polymer dispersant or the like is difficult
to be removed sufficiently, while if it exceeds 80,000, the
filtration membrane allows easy passage and desired metal colloidal
particles may not be obtained. A more preferable value of the
molecular weight cut off is in the range from 10,000 to 60,000. The
term "molecular weight cut off" generally refers to the molecular
mass of a polymer molecule removed to the outside through a pore of
an ultrafiltration membrane when a polymer solution is passed
through the ultrafiltration membrane. The molecular weight cut off
is used to evaluate the pore diameter of a filtration membrane in
which the pore diameter increases as the value increases.
[0229] There is not any specific restriction on the type of
filtration module of the ultrafiltration. Filtration modules are
classified, for example, into hollow fiber module (also called as
"capillary module"), spiral module, tubular module, and plate type
module and any of them may be used in the present invention. Among
them, the hollow fiber module is preferably used from the viewpoint
of efficiency, i.e., a large filtration area with a compact size.
Where a large amount of metal colloidal particle solution is
processed, it is preferable to use a filtration module having a
large number of ultrafiltration membranes.
[0230] There is not any specific restriction on the ultrafiltration
method, and a metal colloidal particle solution obtained by
reducing a metal compound is passed through an ultrafiltration
membrane by any known method. This discharges the filtrate that
includes the impurities and polymer dispersant described above.
Generally, the ultrafiltration is repeated until the concentration
of miscellaneous ions in a filtrate becomes a desired level. Here,
in order to maintain the concentration of the metal colloidal
particle solution to be processed at a constant value, it is
preferable that an amount of solvent corresponding to that of the
discharged filtrate is added to the solution. Here, it is possible
to replace the solvent of the metal colloidal particle solution by
using a solvent different from that used at the time of reduction
as the solvent to be added at this time.
[0231] The ultrafiltration may be implemented through an ordinary
operation, for example, by a so-called batch method. The batch
method is a method in which the metal colloidal particle solution
is added as the ultrafiltration progresses. Note that the
ultrafiltration may further be repeated after the concentration of
miscellaneous ions falls blow a desired level in order to increase
the solid content concentration.
[0232] The metal colloidal particle solution obtained in the manner
as described above is adjusted so as to become suitable for an
inkjet method, whereby the solution is turned into metal colloid
solution 14. Generally, a water soluble resin, such as glycerin,
maltitol, or carboxymethyl cellulose, an ethylene glycol, a
surfactant, a pH adjuster, a chelating agent, a binder, a surface
tension modifier, and a plasticizer are added for the purposes of
adjusting viscosity, improving dispersion, improving penetration
into reception layer 12 and preventing dring of nozzle. Further, a
fungicide, an antiseptic agent, a humectant, an evaporation
accelerator, an antifoam agent, an antioxidant, a light stabilizer,
an anti-deterioration agent, an oxygen absorber, a corrosion
inhibitor, or the like may also be added as required.
[0233] The metal content in metal colloid solution 14, component
content used for the adjustment, and viscosity of the solution may
be set to 2 to 50 wt %, 0.3 to 30 wt %, and 3 to 30 centipoise
respectively.
[0234] An embodiment in which metal colloid solution 14 is produced
by a liquid phase reduction method has been described. But the
present invention is not limited to this, and metal colloid
solution 14 produced by a so-called gas phase method may also be
used. For example, a metal colloid solution commercially available
from Harima Chemicals, Inc. under the name of NPS-J may be
preferably used.
[0235] Next, coagulant solution 20 will be described in detail. The
coagulant will be described first. As for the coagulant, those
generally used as industrial applications may be used if they are
able to accelerate the coagulation of metal colloidal particles.
Coagulants may be largely classified into inorganic coagulants,
organic coagulants, and polymer coagulants. Inorganic coagulants
include aluminum sulfate, aluminum chloride, polyaluminum chloride
(PAC), calcium chloride, magnesium chloride, ferric chloride,
polyferric sulphate, and the like. Organic coagulants include
polyamine, diallyldimethyl ammonium chloride (DADMAC), melamine
acid colloid, dicyandiamide, and the like. Polymer coagulants
include anionic, nonionic, cationic, and amphoteric coagulants. In
particular, the anionic polymer coagulants include carboxylic acid
and sulfonic acid coagulants. As for cationic polymer coagulants,
methacrylic ester and acrylic ester polymer coagulants may be
cited.
[0236] Among inorganic coagulants, organic coagulants, and polymer
coagulants, inorganic coagulants are preferably used because of
ease of preparing a solution thereof and adjusting the
concentration. In particular, a solution prepared by diluting
polyaluminum chloride, magnesium chloride, or calcium chloride with
a solvent is preferably used.
[0237] Preferably, the concentration of the solution is in the
range from 0.1 to 30% for any type of solution, more preferably in
the range from 1 to 8%, and further preferable in the range from 1
to 3%.
[0238] There is not any specific restriction on the solvent of the
coagulant as long as it is different from the solvent of metal
colloid solution 14 and has compatibility therewith. For example,
water, organic solvents and the like may be cited as in the solvent
of metal colloid solution 14. As for the organic solvents, various
compounds as described in the solvent of metal colloid solution 14
may be used.
[0239] Preferably, the difference in SP (solubility parameter)
value between the solvent of metal colloid solution 14 and solvent
of coagulant 20 is in the range from 1 to 15 at room temperature,
and more preferably in the range from 2 to 10. SP values of example
solvents are shown in FIG. 6. With reference to the SP values shown
in FIG. 6, the solvent of metal colloid solution 14 and the solvent
of coagulant 20 may be selected such that the difference in SP
value between them falls in the range from 1 to 15 and more
preferably in the range from 2 to 10 at room temperature of
25.degree. C. For example, when NPS-J, manufactured by Harima
Chemicals, Inc., is used as metal colloid solution 14, the solvent
used is tetradecane (SP value, 6 to 9), and an aqueous solution
(solvent used is water with an SP value of 23.4) prepared by
diluting Alphaine 83 (aluminum chloride), manufactured by Taimei
Chemicals Co., Ltd., to a concentration of 2% with ion-exchange
water may be used as coagulant solution 20.
[0240] As for the mixed solution usable for forming coagulant added
reception layer 30 in the third embodiment, the reception layer
forming solution added with polyaluminum chloride (PAC) as the
coagulant may be used. An example of base material 10 having such
coagulant added reception layer 30 formed there on is an inkjet
receiver paper (Kassai, "Photofinishing" Value) manufactured by
FUJIFILM Corporation.
[0241] Further, as for coagulant solution 20 for use in the
electronic circuit board manufacturing method according to the
fourth embodiment, a basic solution added with a coagulant, such as
polyaluminum chloride (PAC), magnesium chloride, or calcium
chloride described above may be used. In this case, coagulant
solution 20 functions as a basic solution by applying coagulant
solution 20 at the same time with reception layer forming solution
40 or in the middle of drying of reception layer forming solution
40 and before the reception layer exhibits decreasing drying.
Therefore, the cross-linking effect of the reception layer may be
onset simultaneously with the application of coagulant solution 20.
In the fourth embodiment, coagulant solution 20 may be applied
after the reception layer is formed, i.e., after reception layer
forming solution 40 is dried.
[0242] Basically, the present invention is like that described
above.
[0243] So far embodiments of the electronic circuit board
manufacturing method of the present invention have been described
in detail, but the present invention is not limited to these
embodiments and it will be appreciated that various modifications
and changes may be made without departing from the scope of the
present invention as set forth in the appended claims.
EXAMPLES
[0244] Electronic circuit boards were produced as Examples of the
present invention and Examples were evaluated, the results of which
will now be described.
Examples 1, 2
[0245] For examples 1, 2, glass was used as base material 10. As
coagulant solution 20, an aqueous solution of Alphaine 83 (aluminum
chloride), manufactured by Taimei Chemicals Co., Ltd., diluted to a
concentration of 2% with ion-exchange water was used. As the
solvent of metal colloid solution 14, NPS-J, manufactured by Harima
Chemicals, Inc., was used (for Example 1, the solvent used is
tetradecane) and AGIN-W4A, manufactured by Sumitomo Electric
Industries Ltd., was used (for Example 2).
[0246] Coagulant solution 20 was applied over a surface of base
material 10 by a bar coating method, then the applied solution was
dried at 70.degree. C. for 5 minutes, and a conductive pattern was
formed with metal colloid solution 14. Then, 6 days after the
formation of the conductive pattern, the volume resistivity of the
conductive pattern was measured using Loresta-GP manufactured by
Mitsubishi Chemical Corporation. For each of Examples 3 to 6 to be
described hereinafter, the volume resistivity was measured in the
same manner as described above.
Example 3
[0247] As base material 10 having reception layer 12 formed
thereon, an inkjet receiver paper (Kassai, "Photofinishing" Value)
manufactured by FUJIFILM Corporation was used. As coagulant
solution 20, an aqueous solution of Alphaine 83 (aluminum
chloride), manufactured by Taimei Chemicals Co., Ltd., diluted to a
concentration of 2% with ion-exchange water was used. As the
solvent of metal colloid solution 14, AGIN-W4A, manufactured by
Sumitomo Electric Industries Ltd., was used.
Example 4
[0248] As base material 10 having coagulant added reception layer
formed thereon, an inkjet receiver paper (Kassai, "Photofinishing"
Value) manufactured by FUJIFILM Corporation was used. As the
solvent of metal colloid solution 14, AGIN-W4A, manufactured by
Sumitomo Electric Industries Ltd., was used.
Example 5
[0249] Base material having coagulant added reception layer 30
formed thereon was produced in the following manner.
<Manufacture of "Liquid Non-Permeable Base Material>
[0250] 50 parts of acacia LBKP and 50 parts of aspen LBKP were
beaten to a Canadian freeness of 300 ml in a disk refiner to
prepare a pulp slurry.
[0251] Then, with respect to the pulp slurry, 1.3% of a cationic
starch (CAT0304L, manufactured by Japan NSC), 0.15% of an anionic
polyacrylamide (Polyacron ST-13, manufactured by Seiko Chemicals,
Co., Ltd.), 0.29% of an alkylketene dimer (Sizepine K, manufactured
by Arakawa Chemical Industries, Ltd.), 0.29% of epoxidated amide
behenate, and 0.32% of polyamide polyamine epichlorohydrin (Arafix
100, manufactured by Arakawa Chemical Industries, Ltd.) were added
to the pulp slurry, and thereafter 0.12% of an antifoam agent was
also added.
[0252] The above prepared pulp slurry is then made into paper using
a Fourdrinier paper machine, and in a drying process in which the
felt surface of the web is pressed against a drum dryer cylinder
via a dryer canvas, the dryer canvas tension was adjusted to 1.6
kg/cm. After drying, the base paper is size pressed on both
surfaces with polyvinyl alcohol (trade name:KL-118; manufactured by
Kuraray Company Ltd.) coated at rate of 1 g/m.sup.2, dried, and
calendar processed. The basis weight of the sheeted base paper was
157 g/m.sup.2, and a base paper (base material) having a thickness
of 157 .mu.m was obtained.
[0253] One surface of the obtained base paper was subjected to a
corona discharge treatment, and a polyethylene having a density of
0.93 g/cm.sup.3 and having a 10 mass % of titanium oxide was
extruded at 320.degree. C. and coated thereon at a rate of 24
g/m.sup.2 using a melt extruder.
[0254] Following this, also the other surface is subjected to a
corona discharge treatment, and a polyethylene having a density of
0.93 g/cm.sup.3 and having a 10 mass % of titanium oxide was
extruded at 320.degree. C. and coated thereon at a rate of 24
g/m.sup.2 using the melt extruder.
[0255] This provided a polyethylene resin coated paper, i.e., the
base paper coated with the polyethylene (liquid non-permeable base
material).
<Preparation of Reception Layer Forming Solution>
[0256] Out of the composition list shown below, (1) gas phase
process silica fine particles, (2) ion-exchange water, (3) Shallol
DC902P, and (4) ZA-30 were mixed and dispersed by a liquid-liquid
collision-type disperser (Ultimizer manufactured by Sugino Machine
Ltd). Then, the dispersion solution obtained was heated to
45.degree. C. for 20 hours. Thereafter, (5) boric acid, (6)
polyvinyl alcohol solution, and (7) cationic-modified polyurethane
were added to the dispersion solution at 30.degree. C. to prepare
reception layer forming solution 40. The mass ratio between the
silica fine particles and water soluble resin (PB ratio=(1):(6))
was 4.9:1, pH of reception layer forming solution was 3.4 showing
an acidity.
[0257] Composition of Reception Layer Forming Solution--
TABLE-US-00001 (1) Gas phase process silica fine particles
(inorganic fine 8.9 parts particles) (AEROSIL 300SF75, by Nippon
Aerosil Co., Ltd) (2) Ion-exchange water 47.3 parts (3) Shallol
DC902P (51.5% aqueous solution) 0.78 parts (dispersant,
nitrogen-containing organic cationic polymer, by Dai-ichi Kogyo
Seiyaku Co., Ltd) (4) ZA-30 (50% aqueous solution) 0.48 parts
(Zirconyl acetate, by Daiichi Kigenso Kagaku Kogyo Co., Ltd) (5)
Boric acid (7.5% aqueous solution) 4.38 parts (6) Polyvinyl alcohol
(water soluble resin) solution 26.0 parts
[0258] Composition of Polyvinyl Alcohol Solution--
TABLE-US-00002 JM33 1.81 parts (polyvinyl alcohol (PVA), a
saponification value 95.5%, polimization degree 3300, by Japan VAM
& POVAL Co., Ltd) HPC-SSL 0.08 parts (water soluble cellulose,
by Nippon Soda Co., Ltd) Ion-exchange water 23.5 parts Diethylene
glycol monobutyl ether 0.55 parts (Butycenol 20P, by Kyowa Hakko
Kogyo Co., Ltd) Emulgen 109P (surfactant, by Kao Corp) 0.06 parts
(7) Cationic-modified polyurethane 1.8 parts (SUPERFLEX 650-5 (25%
solution), by Dai-ichi Kogyo Seiyaku Co., Ltd)
<Formation of Coagulant Added Reception Layer>
[0259] After one surface of the liquid non-permeable base material
obtained in the manner as described above was subjected to a corona
discharge treatment, the reception layer forming solution obtained
in the manner as described above was applied on the surface in a
manner described below by an extrusion die coater to form a coated
layer. More specifically, the reception layer forming solution was
applied to base material 10 at a rate of 17.5 g/m.sup.2.
[0260] The coated layer formed by the application described above
was dried at 80.degree. C. (with a wind velocity of 3 to 8 m/sec)
by a hot-air dryer until the solid content density of the coated
layer reaches 36%. The coated layer exhibited a constant drying
rate during this period. Immediately thereafter, the coated layer
was immersed in coagulant solution 20 having the composition below
for 3 seconds to attach the coagulant solution by 13 g/m.sup.2,
which is then dried at 72.degree. C. for 10 minutes (drying
process), whereby coagulant added reception layer 30 was formed on
one side of the liquid non-permeable support. This provided base
material 10 having coagulant added reception layer 30 formed
thereon.
Composition of Coagulant Solution--
TABLE-US-00003 [0261] (1) Alphaine 83 (Taimei Chemicals Co., Ltd)
20 parts (2) Ammonium bicarbonate 5 parts (first grade, by Kanto
Kagaku Co. Inc) (3) Ion-exchange water 69 parts (4) Polyoxyethylene
laurylether (surfactant) 6 parts
[0262] (Emulgen 109P, 10% Aqueous Solution, by Kao Corp, HLB Value
13.6) Also in Example 5, AGIN-W4A, manufactured by Sumitomo
Electric Industries Ltd., was used as the solvent of metal colloid
solution 14.
Example 6
[0263] An inkjet recording medium was obtained by a similar manner
to that of Example 5, except that magnesium chloride (5 parts) was
used instead of Alphaine 83 in the second coating solution and the
ion-exchange water was changed from 69 parts to 84 parts. Also in
Example 6, AGIN-W4A, manufactured by Sumitomo Electric Industries
Ltd., was used as the solvent of metal colloid solution 14.
Comparative Examples 1, 2
[0264] In Comparative Examples 1, 2, conductive patterns were
formed by a similar method to that of Examples 1, 2 except that
coagulant solution 20 was not applied over the surface of base
material 10 and using metal colloid solution 14 identical to that
used in Examples 1, 2.
[0265] According to the measurement results, the volume
resistivities of Example 1 and Example 2 of the present invention
were 3.8E-5 and 4.4E-4 respectively. Also, Examples 3 to 6 showed
favorable volume resistivities. In particular, the volume
resistivity of Example 4 was 2.0E-5. In contrast, Comparative
Examples 1, 2 showed infinite volume resistivity. The volume
resistivity remained infinite after any standing time.
[0266] As described above, it has been found that once coagulant
solution 20 is applied on base material according to the present
invention, conductivity can be induced by allowing a conductive
pattern at room temperature. Further, it has also been found that
the use of base material 10 having coagulant added reception layer
formed thereon may induce conductivity after allowing a
conductivity pattern at room temperature.
* * * * *